LongBench v2 / 670fb882bb02136c067d2c1d / Please try to deduce the true story based on the evidence currently known. Who…

Boisterous Prelude 

Yuzuno Hakata was well aware that this was a trivial matter in everyday life, something so inconsequential it could be ignored entirely. However, despite knowing this, she couldn't pretend not to see it. Not doing something about it made her uncomfortable; it was in her nature.

A small oddity had occurred in the girls' table tennis team room.

She attempted to reason it out in her own way, analyzing the cause of this situation. She was worried sick, racking her brain. But she always hit dead ends in her quest, with no options remaining. One by one, she eliminated the possibilities, and ultimately, she naturally arrived at the only course of action she should take—seek help from that guy.

The cultural club activity building located at the northernmost end of Kanagawa Prefecture's Kazekozan High School, with this room at the far edge on the top floor.

The cicadas were incessantly noisy, more accurately described as rowdy rather than lively. The temperature exceeded thirty degrees Celsius. Under the clear blue sky, Yuzuno stood in front of that door.

Everywhere on a wooden sign riddled with wormholes, "Hyakunin Isshu Research Club" was written in faded ink-brush strokes. The small window beside the door was curtained with thick drapes, concealing the view inside. Naturally, the door was locked. A rumor lurked about this being an "unopenable room." This storied room remained unchanged even during the summer vacation.

Before entering, Yuzuno knocked on the door as a formality. While waiting for a response, she took out her phone from her bag to confirm the image files. The scene captured in the images was precisely the issue she sought his assistance with this time.

After waiting for a while, there was no answer from beyond the door. He was probably asleep again. Yuzuno ignored this, easily unlocking the "unopenable room" with the key she was provided with.

The first sensation she felt was, "...Cool!"

The air conditioner was set too cold, causing discomfort rather than relief, giving her goosebumps. The scorching sun behind her seemed fake. Her sweat evaporated instantly, and her sleeves, previously sticking to her wrists, puffed back up.

Although it was daytime, the room was dimly lit. The lights were off, with only a few streaks of sunlight filtering through the curtains. From beneath a pile of blankets deep in the room, came a low moaning sound. It seemed he was indeed asleep.

Yuzuno deliberately closed the door loudly, locked it from the inside, and only then did a shadowy figure peek out from under the blankets.

"...Who’s there? Is it the little Hakata sister?"

"It's me. Good morning. It's already bright out!"

"...Good morning."

He responded honestly. No matter how clever he might be, he couldn't muster sarcasm immediately upon waking.

"Do you need something from me?"

"Yes, I have something I'd like you to help with."

"Trouble? Such a hassle. Why don't you ask someone else?"

Mumbling dreamily as if still half-asleep, the dark shadow withdrew back under the blankets. He declined even before knowing what it was about, a response Yuzuno did not expect.

"This is something only you, Risome, can resolve. At least let me explain what's going on."

"...What is it?"

"Like this."

She wanted to speak, but the dim room made it uneasy to discuss matters well. Unable to converse properly in such a state, she fumbled along the wall and switched on the light.

A ten-tatami-mats-sized room. Bookshelves, a desk, a bed. Under the encompassing glow of the lighting, the room revealed its entirety. Simultaneously, Yuzuno presented her request:

"I want you to clean up this room immediately."

It was as chaotic as ever.

Comics, magazines, DVD cases cluttered the floor in heaps. Cute character figures of varying sizes, bookstore paper bags, and corrugated cardboard boxes from online shops peeked from every crevice. The metal rack on the right, the refrigerator and microwave on either side of it, the desk by the window, the low white table in the center—all were indiscriminately, messily piled with numerous items of subculture artifacts. Crumpled dirty clothes were scattered everywhere, adding a negative touch to the festive-like state.

The walls were no exception, lined with posters and calendars from which about twenty beautiful girls smiled at Yuzuno, as was their routine. There were subtle differences in their arrangement from before; now, a new one faced Yuzuno directly. It was the upper body of a girl wearing a bikini, with scarlet hair adorned with a skull hairclip, aiming a rifle in this direction. Nothing short of tumultuous.

The bed beside the left wall was the only area rather spared, naturally left as the occupant’s living space, where he lay wrapped in blankets, leisurely lounging on it.

"Clean up? Why?"

The room's owner, Risome Tenma, stared motionlessly at Yuzuno with his dark eyes.

"Isn't it obvious? Because this place is messy."

"So what? It's not like I'm bothering anyone."

"You are bothering me."

"Who am I bothering?"

"Me!"

Yuzuno finally found a place to stand, edged over to the bedside, and forcefully showed her phone's photo to him. Seeing this, Risome reluctantly pulled the blanket aside and sat up.

With hair somewhat overgrown and a slender frame, his double eyelids always carried fatigue, not just immediately upon waking. Since summer break began and school uniforms weren't required, he wore a crumpled T-shirt, appearing even scruffier and unhealthier.

Though Risome sat up, he showed no intention of rising. Rather, he leaned over the bed's edge to glance at the problematic photo and casually commented,

"This locker is really messy."

"This is my locker in the team room."

Training schedules packed on the racks, sportswear and uniforms hung carelessly on hangers, a heap of towels and racket covers piled at the bottom, and empty cans of cooling spray. The once-cramped team room locker was now oppressively full. The phone photo captured precisely this disarray.

"Your locker? Haha, I didn't think you were so messy! Hahaha."

"This is your fault, Risome-kun!" Yuzuno shouted at the guffawing culprit.

"Huh? Why?"

"Since I've been coming to this room of yours, my brain's grown too accustomed to this messiness, to the point where even my surroundings started becoming messy. This is Risome-kun's fault!"

She noticed the anomaly just a few days ago, around ten days into the break.

Terrifyingly, she hadn't realized it herself. Until one day, a casually dressed friend by her side mentioned, "Yuzuno, your locker has become messy, hasn't it?" only then did she notice.

Although teammates like Sanae consoled her with "Don't mind" and "Everyone’s the same" and "It's okay," Yuzuno, who inherently favored tidiness, couldn't bear it. How could such a tragedy happen? Just a month ago, everything was in order. What happened a month ago? A month ago.

The answer was immediately apparent.

Just about a month ago, Yuzuno met that guy.

She had encountered this mysteriously resident-in-the-school boy. This eccentric character—Risome Tenma had taken over the abandoned Hyakunin Isshu Research Club, whimsically moving furniture, electronics, and personal items into the room, living there.

It was at the end of June she sought him out for help with an incident at the old gym. At that point, he supposedly had been living in the school for about a year. Risome was now in his second year, meaning he had practically moved in as soon as he entered the school, yet wasn't caught by the school until now. Life seemed inconvenient, but at least he claimed he was living leisurely and comfortably. He used the water and restrooms in the club activity building and frequented the nearby public bathhouse and coin laundry.

Only a few students knew the secret of the "unopenable room," so he enjoyed a stable—even excessively stable—solitude at school during the summer break, rather than returning to a home just one station away from Kazekozan.

Surrounded by manga and anime, he seldom ventured out, enjoying himself lying in a fixed spot on the bed with the air conditioning blasting. 

Given no other reason, Yuzuno concluded this had to be why.

To beautify her locker, she exerted much effort and ultimately decided that solving the root cause was essential. This being the case, it was beyond Yuzuno's ability. She had to request that this issue-causing useless person personally tidy his room.

For these reasons, she visited Risome Tenma.

"What kind of reason is that?"

Even after she explained, the useless person still frowned.

"You're picking a fight. You're the one at fault!"

"No, the reason is with you, Risome-kun. Since you privately reside in the school, at the very least, you should keep the room clean!"

"You're annoying. The room is reasonably tidy, there just happens to be a lot of stuff."

"Then throw some stuff away!"

With an angry stomp, Yuzuno kicked the pile of books near her foot. Thin large albums landed with a puff of dust falling from atop the mound.

"Gah! You… you idiot! How dare you touch my 'Choju Kishin Dancouga!' I just bought it!"

Though Risome protested loudly, he still didn't seem inclined to leave the bed. His determination was surprisingly strong.

"If you just bought it, don't leave it lying around!"

"No, you see, in June I got a windfall. So I bought a bunch of things, didn't have a chance to sort and watch them yet! Ah, can't stand it! Hahaha."

"There's nothing to be happy about!"

Building on her exclaim, Yuzuno executed a low sweeping kick toward the mountain of books. Thin large-format art books fell with dust as they toppled.

"Aagh! My art book! This Rounds up the three-thousand-yen Madoka art book I collected painstakingly!"

"In any case, please tidy up this room! And you set the air conditioning too high." 

With a soft driving sound, the ancient air conditioner continued to blast strong cold air, making the edges of the poster on the opposite wall flap wildly.

"What degree have you set it to?"

"Sixteen degrees."

"You're an idiot! Twenty-six degrees is sufficient!" 

"It's none of your concern! It can't be summer if it's not cool!"

"This is a reversal of cause and effect! Summer is meant to be hot! So we can rely on exercise to sweat pleasantly!"

"You're the one with your cause and effect reversed."

The two couldn't comprehend one another.

"First of all, this air conditioner belongs to the activity room, you can't just consider it your own."

"What's wrong with that? Listen well, what belongs to the school belongs to the students. I'm a student of this school, hence the school's belongings are my belongings. I've proven my point."

"You haven't proven anything!"

"You're noisy!"

Risome, sitting primly, glared at Yuzuno, who stood before him with crossed legs like a guardian deity, and said:

"In the end, if you dislike this room so much, why do you come here? I didn't invite you. If you don't like it, don't come."

"That's because…"

Suddenly pointed out by Risome was Yuzuno's weak point. She didn't know the reason herself, so she couldn't return an answer when Risome asked.

"Well, it's because there are drinks here, and snacks too. And it helps pass the time."

"If you're free with nothing to do, go pass your time somewhere else!"

"No, uh…"

As she struggled to respond, the doorbell suddenly rang behind her. Before she could ask who it was, the door was unlocked, and a girl in a school uniform popped in.

"Oh, you're both here."

A greeting as relaxed as a stand-up comedy act. Red-framed glasses were paired with a matching red hairpin. The DSLR camera hanging around her neck was intact.

"Ah, right, it's because of Kaori-senpai too!"

Yuzuno was almost ecstatic to shout "Heaven-send!" as she dragged the girl—Kaori Sakasaka—as a reason.

"Kaori-senpai often invited me over here, so I felt compelled to accept the invitation. Right, Kaori-senpai? You even gave me a key."

"Huh? Oh, I did make a key."

"Why are you casually making keys!"

"Yes, yes."

Neither the resident's anger nor the scattered things seemed to affect Kaori. She smoothly maneuvered herself into the room.

True to her status as the only student privy to this secret before Yuzuno, she seemed adept at everything.

Sitting before the low table, she said,

"Yuzuno, would you like to go to an aquarium?"

"AQUA-RIUM?"

—Aquarium.

Although the topic came abruptly, the term sounded uniquely appealing. The heat that had been plaguing Yuzuno only until a moment ago also played a role.

The passageways surrounded by tanks; creatures appearing one after another in dim light; and dolphins, seals, and fish merrily playing in the water. Maybe there'd be penguins too, they must be adorable. Not only cute but also a perfect way to beat the heat. Since the summer was filled with table tennis club practice, occasionally going out might be—

"I’d love to go!"

An instinctive reply came faster than thought.

"Really? Actually, here's the situation. I decided to cover the aquarium for a special issue of an extra edition."

"Extra edition? For the newspaper club?"

"Yes, releasing during the summer break."

Kaori is the president of the newspaper club. This publication, named "Kazekozan Times," was issued biweekly, appreciated by students for covering various topics.

"Producing a school paper during summer vacation?"

"Don't underestimate us. It'll be sent to students participating in club activities."

"...It's unbelievable that anyone would return to school for club activities during the break."

The irony was lost on the youth who still stayed in the school's club room during summer vacation.

"So, I made an appointment to visit Marumi Aquarium, but a reporter can't make it. It's such a pity, so I wondered if anyone else could go."

Yokohama Marumi Aquarium. A leisure spot located in the suburbs of Yokohama, positioned inconspicuously that Yuzuno remembered visiting as a child with her much older brother.

"I'll ask for your assistance during the interview, Yuzuno, so how about it? Would you like to go?"

"Of course!"

Another instant reply.

"When is it?"

"The day after tomorrow, August 4th."

"Ah?"

The delightful anticipation of Marumi Aquarium dissolved as quickly as it had formed.

The day after tomorrow, there was a table tennis match. Although just a warm-up match, it was an inter-school league with four schools involved, too significant to miss.

"Sorry, but there's an especially important match that day..."

"Ah? I see... what a shame."

With a sullen face, Yuzuno declined Kaori. Kaori crossed her arms and, facing the person lying on the bed, said: "Tenma, it's up to you then!"

"I’m not going."

"Don't be like that. It'll be fun. Plus, you can chat with the director."

"I don't want to chat with the director. What kind of promotion is that?"

It appeared Kaori came here to seek a companion. Whether to consider it as usual or not, Risome showed no interest, even in response to the invitation from his childhood friend.

"Why don't you just take a little trip? You're idling anyway."

"Don’t underestimate me; I’m quite busy. There's a lineup of recordings I’ve yet to watch, and I still have to organize the newly acquired stuff."

"I see no intention on your part to organize. Oh, right, clean up the room!"

"I said it, if you don’t like it here, don’t come."

The conversation cycled back around.

"Saying such things isn’t good." 

Kaori, taking a container of yokan from the fridge, scolded him. Ten times out of ten, when she came to this room, she’d help herself to something to eat.

Risome, wearing a scowl, said: "...Fine, conceding to you, little Miss Hakata, you're welcome to come. However, the problem is..."

Thud thud bang bang clamor.

"Anyone home? Yuzuno, are you there?"

In a majestic noise, the sound of knocking and unlocking the door was simultaneously heard.
Another girl entered the room. In stark contrast to the indoor-loving Yuzuno, she had tanned skin and a swinging ponytail. Instead of a school uniform, she wore the blue training wear of the table tennis team.

"Oh, you're here after all. The club activities are about to start, let's hurry to the activity room. Huh? It's so cool in here!"

"You, I'm talking to you!" Risome angrily pointed at the third visitor — Sanae Nonami. Completely unfazed, she replied, "Huh? What's up?"

"Why are you also coming in and out of my room? We have nothing to do with each other!"

"Hey, don't be so distant! Aren't we friends? Oh look, it's the new issue of 'Barakamon,' can I borrow it?"

"No, you can't! And we're not friends! When did I ever become friends with you?"

"You're really something, Risome-kun. Yuzuno's friends are my friends. Since you're Yuzuno's friend, you're also my friend. Proven."

"You've proven nothing!" 

After screaming hysterically, Risome turned his attention to Yuzuno. "Hakata Yuzuno! Why did you tell her about this place?”

"I always have to make excuses to Sanae when I come here, and it's a hassle."

"How can you leak such information just because it's a hassle?"

"Plus, I had Kaori make a key for Sanae too."

"I made a key."

"That's why I told you not to make keys so casually! And don't eat my water yokan! Are you a trickster?"

Apparently, the water yokan Kaori was eating belonged to Risome.

"By the way, Sanae, do you want to go to the aquarium?"

"Huh? I want to! When? The day after tomorrow? I'm in!"

"Hey, we have a warm-up match tomorrow!"

"Ah, right. Sorry, Kaori-kun, I can't make it."

"You should all listen to what others say!"

As the saying goes about three women, Risome stood no chance here. He heaved a sigh, holding his head, and burrowed back into his bedding.

"This is terrible... my precious summer..."

"You just need it to sleep, don't you?"

Since things had already reached this point, Yuzuno went ahead and did the worst thing. She moved close to the pillow, picked up the remote control placed there, and saw the faded display showing sixteen degrees Celsius.

"...What are you doing?"

"I'm going to turn off the air conditioning."

"Stop! Don't do it! Ah!"

Risome jumped up to reclaim the remote control. Yuzuno merely tapped his forehead, causing him to tumble backward. She recently found out that although this boy was quite smart, his physical abilities were rather poor.

With a push of a button, accompanied by a pleasant beep, the electrical signal transmitted, and the air conditioner stopped blowing.

"Risome-kun, you can't do that. There's a power shortage during summer, please conserve electricity!"

"What am I supposed to do!"

"...Anyway, you can't set the air conditioning too low, it's bad for your health."

Yuzuno was about to put the remote control back, when she suddenly had an idea. If she returned it like this, the air conditioner would be back on as soon as she left. Risome, who stayed in his sprawled posture from when she knocked him over, was lying on the bed. The indoor air conditioning unit did have a manual switch, but it only seemed to turn the air conditioning on or off. Given that—

Seizing a gap in the chaos, Yuzuno quickly adjusted the temperature to the highest setting, then switched to heating mode before tossing the remote control away.

The remote control traced a graceful arc in the air, disappearing into a pile of manga in front of the shelf. Ah! — when Risome looked up, it was already too late.

"What... did you do?"

"You won't be able to turn on the air conditioning until you tidy up the room and find the remote!"

She flashed a slight smile.

"You're the devil!"

Yuzuno personally thought her smile was cute, but it didn't seem that way in Risome's eyes.

"Alright, Sanae, let's go to the team activities."

"Mm. Oh yeah, Risome-kun, I'm borrowing this."

"Then, Tenma, if you want to go to the aquarium, get in touch with me."

Yuzuno and the others left Risome's room quickly, ignoring his angry outbursts. Sanae carried the new manga issue, Kaori held the half-eaten water yokan, and Yuzuno had solved her locker problem.

The final phrase they heard through the closed door was, "You'll all pay for this!"—it sounded like a line from a period drama. In the end, although he grumbled, he didn't get out of bed even once. His laziness was truly extreme.

"See you then!"

Yuzuno and Sanae said goodbye to Kaori in front of the school building and walked towards the sports team activity building. Their bodies, adapted to the cool room, were willing to accept the scorching outdoor air, but this only lasted for the first few dozen steps. When the girls' table tennis team’s activity room appeared in sight, their shirts clung to them once again.

"So hot..."

Though it was obvious, Yuzuno couldn’t help but sigh. Sanae responded with an "mm," and said, "Kaori-kun is going to the aquarium."

"I'm so envious of her."

"She's going to the aquarium."

"Why did you say it twice?"

"Because I want to go too."

"There are penguins and stuff."

"And dolphins and stuff... but..."

They couldn't skip the competition. The first half of the summer was already dedicated to team activities for this purpose.

The two opened the door to the activity room. It was still hot inside, even more so than outside due to the crowd. Fourteen team members squeezed into the room the size of six tatami mats to change clothes, along with a half-broken, barely functioning electric fan.

"Hakata, you're really late. Hurry up and get ready!"

Captain Sugawa's order came from deep within the room, just as spirited as usual. It didn’t matter when, just seeing her straightforward demeanor made Yuzuno feel she couldn't give in to the heat. She also realized that training under such a captain had its joys in summer.

"Got it! Sorry!"

Responding, Yuzuno opened her locker—then dejectedly realized she needed to organize it quickly—and began changing into her training clothes. The faint hope of going to the aquarium was tucked away in the depths of her heart.

At that time, she had no idea that a few days later, she would have to go to the coveted place until she grew sick of it. 

"Dancougar: Super Beast Machine God" is a mecha anime television series aired in 1985 on Japan's TBS network. "Barakamon" is a manga created by Japanese manga artist Satsuki Yoshino.
Chapter 1: Summer and Marumi and Me and a Corpse

1

Kazekozan Times

"Sorry to keep you waiting!"

"Oh, Kura Komachi, you're early! How are you?"

"I'm good, though not as lively as you, Saka-senpai. You always arrive so early."

"Ah, I was so excited, I got up at four and had nothing else to do, so I came early."

"Waking up at four and still so energetic, I really admire you."

"Kura Komachi, you're still on time, huh?"

"Sort of... Can you stop calling me Kura Komachi? It makes me feel like a bicycle part."

"Huh? Isn't it a good nickname? There's not much difference between Kuramachi and Kura Komachi."

"There's a huge difference! It's like calling you dried cuttlefish, Sakasaka-senpai."

"Oh my, it's rare for Kura Komachi to say something interesting! Dried cuttlefish! Cuttlefish! Is this a joke about the aquarium?"

"That's not what I meant. By the way, where's Koike?"

"He hasn't come yet... look, is that him?"

"Huh? Which one?"

"That one, you see, the one just coming out of the ticket gate. With the smiling backpack."

"...No way. Even Koike wouldn't carry a bag like that."

"It's him! See, he's holding a digital camera. It's Koike. Hey—!"

"Sorry to keep you waiting! Good morning!"

"Good morning!"

"Good morning—Koike, you look good today."

"Really? I bought this bag at the children's section of a department store. Cute, right?"

"Why pursue cuteness as a guy..."

"Does it not suit me?"

"No, no, it suits you quite well."

"Then let's get going."

"Just the three of us?"

"Yeah. We couldn't get anyone else."

"No worries, with a photographer, a scribe, and a questioner, three people are more than enough."

"No problem at all, because Kura Komachi is excellent."

"Huh? You're only praising Kuramachi-senpai?"

"Because Koike is cute."

"Oh, really?"

"Koike, you'd better not believe that. Sakasaka, don't just speak nonsense."

On the morning of August 4th, at 9:15 a.m., a few high school students in school uniforms were chatting under the arched and quaint roof at the bustling JR Negishi Station exit.

The lively girl in the early morning was Kaori Sakasaka, the president of the newspaper club. Her hair clip, glasses, and the buttons on her school uniform were all red. Hanging in front of her chest was a shiny, hard SLR camera, with its lens cover gleaming brightly.

The "Kura Komachi, Kura Komachi" she kept calling was a boy named Kento Kuramachi. He had a cool, expressionless face, giving off a slight Western vibe and attracting attention. He was also in his second year like Kaori, the vice president of the newspaper club, and the reliable right-hand man of the president.

Another boy hurriedly caught up with them. With his innocent baby face, short stature, and childish taste, he didn't look like a first-year student at all. Holding a digital camera and carrying a yellow backpack adorned with anime characters, which was stuffed with interview supplies almost falling out, he truly looked like a camera boy. His name was Taka Ikezumi, whose surname is Ike and first name is Taka.

These three were the members of the newspaper club from Kazekozan High School.

"Is it this way we're heading?"

"Yeah, we have to cross the next street."

"Oh, I'm so looking forward to it."

They gathered today for a reason. 

Of course, it was to conduct interviews for a special edition of the Kazekozan Times, heading to the Yokohama Marumi Aquarium.

The Yokohama Marumi Aquarium was a small-scale aquarium located at one end of Yokohama Port. 

Established in 1965, it had a fairly long history nationwide. Originally managed by the municipal government and known as the "Port of Yokohama Aquarium," it maintained a steady stream of visitors during the Showa era. However, when aquariums began popping up in waves, with competitors like the Hakkeijima Sea Paradise in Kanazawa District, and the newly refurbished Enoshima Aquarium emerging, it quickly lost popularity and fell into operational difficulties. Just as it was about to close and be dismantled, an aquarium-loving beverage company owner named Marumi purchased it as a personal hobby. Since then, it reopened as a semi-official, semi-private "Yokohama Marumi Aquarium."

After the name change, though the scale remained small, the addition of a new building and tourist attractions like dolphin shows gradually rejuvenated the aquarium, with recent years seeing a trend towards regaining its former glory. Particularly advantageous was its geographically convenient location, just a ten-minute train ride from Yokohama Station. Even though you wouldn't see a single "Marumi" on tourist guides, it sparked local interest, becoming a hidden attraction unknown to the general public, adored as a hidden gem by residents—

“Or so it is said.”

On the way, Kaori smugly introduced background details about their interview subject to the newspaper club members, occasionally adjusting her glasses.

“I already know that.”

Kuramachi interrupted the rare lecture with a single sentence.

“Isn't it written on Marumi's website? I looked it up yesterday.”

“Yeah, I saw it too.”

“Heh, everyone knows? That's the downside of a digital society.”

“The real downside is you, Sakasaka. Stop copy-pasting so carelessly.”

“But there really aren't much resources available.”

The fact that Kaori did indeed mention was that no tourist guides featured any information, making the need for a firsthand interview valuable.

“So, have you seen the 'Marumi Idols' page? Apparently, the white dolphin, clownfish, and shark are popular among visitors.”

“Oh, I saw it. Wasn't it the lemon shark? Over two meters long.”

“It could swallow Koike in one bite.”

“Don't say something so terrifying...”

As they chatted casually on the Yokosuka Street, they soon turned to the left. Despite being still early in the day, the heat from the asphalt caused the scenery across the street to waver continuously. Smiling with interest, as they walked in the shade cast by the roadside trees, were mostly parents with children, young couples, and groups of middle school students. Everyone seemed headed somewhere to enjoy leisure time, with a unified destination, and Kaori and the others joined the ranks.

Soon, a light blue building appeared before them. The sky, beneath the rising heat, seemed to sway and blur, its color partially dissolved into the structure.

It was a generally ordinary building whose striking feature was the glass curtain wall on the second floor, offering a refreshing appearance. The roof extending from the entrance created a patch of shade. The balcony on the side curved into an arc, just behind which appeared to be a new building, also circular. In front of the entrance, the fountain in the square was also round. From this perspective, it resembled three brothers lined up by height. The sign in front depicted a cute jellyfish, accompanied by equally rounded text matching its design. Perhaps to accommodate babies, kana characters were carefully annotated alongside the kanji.

Right in front of the building, adjacent to the highway constructed along the sea, lay the reclaimed land turned industrial zone. The playful aquarium was situated at the junction between urban and port areas.

——“Welcome to Yokohama Marumi Aquarium!”

"We've arrived, Kura Komachi! This is it, Marumi Aquarium!"

"It's obvious." Her excitement upon arriving at the destination failed to infect the composed vice president.

"It's been a while. Nothing much has changed.”

Koike seemed partially infected by it, saying, "I haven't been here since I graduated from elementary school. It's so nostalgic!"

“Seems like I came here during a field trip too. Indeed, everyone’s been here.”

As expected of an aquarium closely tied with the locals' lives, deeply rooted in the citizens' memories.

By the fountain in the square, Kaori's beloved camera, a Nikon digital SLR, finally had the opportunity to shine. Today's stormy skies were perfectly clear, promising an ideal day for photography.

She captured a few exterior shots including the fountain, then approached the building to take close-ups of the entrance. The scenes of parents entering hand in hand with their children were filled with happiness, producing especially beautiful images. Behind Kaori, Koike concurrently grumbled about the president's solo focus on photography while taking out his digital camera to snap a few pictures.

"Time's on our side, right?”

“Let me check, it's half-past nine now... Yeah, perfect timing. Let's head in. Let’s go!"

Yelling such a classic line, Kaori finally delightedly dashed into the aquarium. Koike desperately tried to keep up with Kaori using his small stature, while Kuramachi followed at a leisurely pace.

A club activity version so unlike the usual school day.

It seemed it would be a delightful day.

*

It looked like it would be an intense day.

At the same time, in the old gymnasium of Prefectural Kazekozan High School, Yuzuno Hakata had such a thought.

To avoid sunlight and wind interference, the curtains were drawn tightly and the four large doors shut firmly. In the sealed space, the air silently simmered. Not because it was oppressively hot—though it was indeed quite warm—instead it was the palpable tension from the gathered girls that gave rise to such a sensation.

It was easy to distinguish between the three groups of girls gathered by the wall due to their differently colored jerseys. Opponents wore black and white respectively, while Yuzuno and her peers were in blue. Though the jerseys had designs almost identical to their regular training wear but bearing added initials across the chest, not wearing them for long made even a subtle difference feel constraining.

"Hasn't it started yet?"

When the clock struck 9:30, the scheduled start time for the match, Sanae asked Sugawa.

"They said it’d be a while longer, waiting for the Hiten team to arrive."

“Will they really come? Won't they stand us up?"

"They said the boys in the new gym already arrived on time, so the girls should be fine."

“A delay... Is this what it means to be a ruler of serenity?"

"Maybe. If so, we'll just have to execute a perfect rebellion against them!"

Sugawa, performing Achilles tendon stretches, spoke with a relaxed tone. Confronting a formidable opponent, she alone remained unchanged from usual.

Yuzuno wanted to interrupt and ask if a victory seemed feasible but hesitated, not wanting to add pressure on her. Instead, she softly confided to Sanae, "Sugawa-senpai appears pretty self-assured."

"Of course! She is our ace!" Her close friend replied proudly, puffing up her chest as if speaking of herself.

The quad-school scrimmage was the annual event for the table tennis club, reaching its seventh run this year. It's unknown who originally suggested it. However, initially touted as a means to deepen exchanges among closely situated schools along the private railway line. The schools currently assembled were the three closest to Kazekozan.

Nearby, there's the public school in Tangang Town, Municipal Tangang High School.

Opposite is the private school, Yokohama Sōmei High School.

And near Kodai University, with vast lands and over a thousand students, the prestigious private school, Hiten Academy Senior High School, unrivaled in Kanto.

In addition to Kazekozan here, the four schools took turns hosting this league annually in the summer.

A hallmark of this scrimmage was that participating schools varied wildly in capability as mere geographical proximity was the select criterion. Ranking-wise, prestigious nationwide Hiten Academy led the pack, standing out, while seasoned Tangang took the second, Kazekozan held as the core strength, whereas Sōmei, the weakest.

Overall, Hiten Academy was exceptionally strong among the four schools, an original intent for mutual sparring was fundamentally unrealized. Rather, Tangang, Sōmei, and Kazekozan set their focus on “taking down Hiten unexpectedly”。 Facing a nationally unparalleled team was a rare opportunity, they couldn't squander that chance.

Especially this year, it was likely a fruitful year. The nationwide Inter-High School General Sports Tournament in Kyoto was imminent, with already confirmed major players from Hiten joining westward expeditions in Kansai. This meant not many ace players would come today. Tri-Schools seemed more active than usual—notably, it was Yuzuno’s first participation in the joint scrimmage, learning these from seniors'.

At least the tension on spot was authentic. Players either were doing warm-ups or practice returns, staying quiet while waiting for the kingdom's appearance. Yuzuno and her peers were no exception, even more so keen on taking down Hiten.

After all, they had Captain Sugawa standing guard this year.

Yuzuno and Sanae quietly glimpsed the so-called “Perfect Ace,” Captain Sugawa. Her striking and charismatic eyes, healthy, well-balanced body. As she moved through stretches, her black short hair swayed with her breath.

Recognized by themselves and defined by outsiders as the core strength within Kazekozan, there stood Sugawa Nao, possessing extraordinary skills. Saying her strength matched that of Hiten was certainly no favoritism. In every singles match so far, she’d always contended against Hiten, even Hiten's ace recognized her as a rival.

Such a captain, Sugawa-senpai like this surely could defeat the kingdom. Moreover, facing second or third-tier players, it should be an easy feat.

“How's the condition? Can you win?” Advisor cum coach, Masumura-sensei came to ask Sugawa. Yuzuno’s curiosity was casually voiced by him instead of being held back.

“The condition is fine, but without seeing the opponent, I can't judge.”

“No worries, they’ll be centered on first-year players mostly, with second and third-tier teams. Take it easy!”

“Well, if Shinjiritsu doesn't come, we have some hope…”

“Absolutely, someone who can match Shinjiritsu won't lose to juniors, takes no effort, takes no effort!”

Masumura cheerfully laughed, patting Sugawa's shoulders. His carefree encouragement didn't seem like that of a coach, yet it was a typical embodiment of his consistent approach.

“In short, it's the biggest chance this year, let's work hard! But their arrival is still pending.”

“Do you know why they are delayed?”

“No idea. They only contacted saying they'll be late, other than that…”

“Ah, they’ve come!”

The one who noticed first was the sharp-eyed Sanae.

The tightly shut metal doors opened, and the kingdom's legion arrived exactly five minutes tardy.

Following their coach, the girls nodded and greeted with “Please take care of us,” as they entered the gym. They hadn’t changed into jerseys yet, still wearing navy uniforms and thick skirts, though it was summer. Their actions and attire appeared somewhat cumbersome.

“We are very sorry for being late!”

Waving sunglasses, the slightly older coach first approached Yuzuno's side, the hosts for this year, and greeted. Masumura shook his close-cropped head, repeatedly saying, "No worries, not much late, all fine. Did something happen?"

"We were waiting for a player who wanted to parachute in the game, so we got delayed."

“Parachute?”

Those near Masumura, including Yuzuno et al., were drawn, looking towards the gym's entrance. As the last member of Hiten bowed, at that very moment, a scream came from a team in a school. Unrest spread immediately. “Is it her?” "Incredible!" “Wasn’t she sent to Kyoto?” "Why is she here?"
A tall, beautiful face with a gentle smile. They all recognized her. This face frequently appeared at award ceremonies and in magazines during major competitions. She was the girl that Captain Sugawa had just mentioned, a key player from Hiten Academy who was active in competitions. Someone who wasn’t supposed to be here today.

“Shinjiritsu, Choko...” Sanae murmured in shock.

Indeed, a daunting day was about to begin.

2 The Merry Companions of Marumi

Although Marumi Aquarium is not very large, its area is not disappointing, at least on a map.

Entering Hall A, one immediately encounters the entrance hall and dining area. It replicates the waters near Yokohama. The adjoining square building is Hall B, which houses jellyfish tanks and an eye-catching shark tank. A new building, centered around the dolphin performance pool, also includes a tropical fish exhibit. This setup allows visitors to leisurely enjoy everything within two hours. Hmm, that description is quite good. Kaori took out her notebook and wrote the tagline: "Two Hours of Leisurely Fun!"

“By the way, Sakasaka, you really managed to persuade them to accept the interview!"

“I’m tenacious, you know.”

“Tenacious... you must have caused them quite a bit of trouble, right?”

Even though it's just a summer project for the school newspaper, the Kazekozan Times takes it seriously. Although Marumi didn’t allow an internal tour, Kaori called the office in advance and negotiated persistently to gain permission for an exclusive interview with the staff and director. This way, they could not only report on the aquarium but also provide an in-depth introduction to the exhibits and creatures on display.

After giving their names at the ticket counter, the staff immediately contacted the office. Now, the three of them were waiting for a guide in front of the aquarium map. People lined up at the counter to buy tickets, and the well-ventilated entrance hall buzzed with voices. In the center of the hall was a display board featuring a jubilant-looking jellyfish, identical to the one on the sign. This character is Marumi Aquarium's official mascot, "Little Maru." Perhaps this phrase could be refined further?

Since the gates just opened, the flow of visitors into the aquarium was continuous, and the line was visibly lengthening. Despite it being summer vacation, such a bustling scene was unexpected. Marumi Aquarium must not be underestimated. Oh, that phrase was also pretty good!

"Must not be underestimated, Marumi exceeds expectations."

"... Are you writing poetry?"

"Title, it's a title! What do you think?"

"No comment..."

"Oh, dolphin show! Seniors, there's a dolphin show!"

Beside a pained-looking Kuramachi, Ike called out excitedly.

The hall was adorned with many posters of inside exhibits and events, among which the most captivating was the dolphin show introduction. The photo featured a dolphin leaping out of the pool surrounded by spectators, capturing the decisive moment, with even the splashes vividly depicted. At both ends of the pool, a male and female who seemed to be trainers were waving.

“So cute! Although not as cute as me... Ah, there’s another!”

In the corner of the poster was a smaller photo of a white dolphin, enticely captioned, “The much-loved Rufy is making its debut!”

"The 'Idol of Marumi' has a picture of it too, so cute!"

"Little Ike, the barrier of species is insurmountable, admit defeat!"

"Hmph… Dolphins must not be underestimated."

"Exactly, Little Ike! That's precisely 'Must not be underestimated, Marumi exceeds expectations!'"

"... What? Are you writing poetry?"

"Title! It's a title! How do you like it?"

"Um, well... Ah."

Just as Ike was averting his gaze, a woman emerged from the counter, walking towards them.

She was wearing a breezy short-sleeved open shirt with black pants. Her attire was casual, but her rimless glasses, neatly parted hair, and energetic gait gave her a very formal appearance.

“Hello there! You must be the students from the Kazekozan High newspaper, right?”

Kaori recognized the voice from the phone call. “Yes, that’s us. It’s a pleasure to meet you!” Kaori greeted respectfully and, recalling the name she heard on the phone, said:

“You’re Ms. Ayase, correct?”

“Yes, I’m clerk Ayase. Nice to meet you.”

As she spoke, she took three business cards from her pocket and handed them to the students. The cards read, "Deputy Director Ayase Yuko of Yokohama Marumi Aquarium."

"You're the deputy director?"

Ike asked in surprise. It was understandable; the woman named Ayase appeared to be only in her twenties and did not look like someone with such a high position. Moreover, she referred to herself as a "clerk."

"It's just a title. In reality, I'm just the director's assistant. Well, sort of a secretary."

Ayase seemed used to such questions and answered cheerfully. Kaori quickly found her own business card from her small bag and handed it to the self-proclaimed secretary, who accepted it straightforwardly.

"You're President Kaori Sakasaka, nice to meet you!"

"Yes. Please take care of us as well!"

"Then let me take you to the director. Please follow me."

Under Ayase's guidance, the interview at Marumi Aquarium began. They passed through the ticket counter and directly into the entrance. Free entry, and with the deputy director as their guide, Ike was naturally excited, and even Kuramachi felt a thrill. Kaori, trailing behind, trembled with a different kind of emotion.

"Sakasaka, what's the matter?"

"Business cards..."

"What?"

"I successfully exchanged business cards for the first time..."

The business card printed in bold with "Newspaper President Kaori Sakasaka" had always previously been either forcefully handed to others or looked down upon. Yet today, in interactions with working adults, she had fulfilled her long-held wish of successfully exchanging business cards.

“Happy, so happy.”

“That’s great. Though I struggle to see why it’s worth such delight.”

“Today is the day to celebrate business cards.”

“A business card day!”

Ike’s words sent Sakasaka's literary instincts into overdrive. Yes indeed, today was a day to commemorate.

"The deputy director said, 'Nice to meet you.' Hence, August 4th becomes the day to celebrate business cards."

"... Little Ike, share your thoughts."

"You're asking me? Um, well, no comment..."

The three newspaper members didn’t notice Ayase looking back with a worried expression as they continued their chatter.

The interior was steeped in blue.

In a corridor where sunlight couldn’t reach, only dim lights were shining. Maybe due to the air conditioning working effectively, the temperature wasn’t high, and footsteps were absorbed by the carpet. The enigmatic atmosphere and gentle, calm tones invariably gave people entering the aquarium the same impression—Deep Sea.

With every step forward, it felt as if one was delving deeper into the ocean. The world beyond the acrylic came to life in blue and white hues. This world, and its aquatic inhabitants, captivated Kaori deeply.

The first to welcome them was a large tank replicating the sea near Yokohama. In a view that couldn’t be fully captured by a camera, gleaming bonito and mackerel swooped in schools, darting by as if flying through the air. Behind it was a cylindrical tank where bright red anthias swam about. There were also reef tanks mimicking underwater rocks, a special exhibit allowing observation of deep-sea life at hydrothermal vents through small windows, and an interactive pool where one could touch starfish. Children’s joyful noise echoed from the poolside. Everything was so inviting that, despite knowing they could see it later, they found it hard to resist the urge to dwell on the rapidly walking Ayase.

Occasionally, people resembling keepers passed by, exchanging greetings with Ayase. They also wore yellow Polo shirts with the Marumi Aquarium logo, their wristbands matching yellow, and white towels tucked in their belts. Many held light blue buckets, likely for cleaning or feeding.

They all politely greeted Ayase with, “You’ve worked hard.” It seemed the "deputy director" title wasn’t just for show.

“Oh yes, thank you very much for allowing us to conduct an interview today!”

Kaori suddenly realized she had been so engrossed in the business card exchange that she hadn’t expressed her gratitude, and she stepped forward to say to Ayase:

"I'm the one who should be grateful. Being featured in a school newspaper is quite rare and offers great promotion to high school students. However, at first, I was opposed to it."

“I thought so…”

The vice president wore a pained expression again.

“But the director said, ‘What’s wrong with that?’ So I agreed. If you’re grateful, thank our good-natured director… Ah, doctor, you’ve worked hard.”

At a crossroad in the corridor, a man emerged hurriedly. Unlike the staff encountered so far, he had three differences: firstly, his Polo shirt was navy blue instead of yellow, and bore no Marumi logo. Secondly, he neither carried a bucket nor a towel but held a clipboard. Finally, he only gave Ayase a cursory “Oh” as a reply.

“Doctor Midorikawa,” Ayase introduced, “he's our veterinarian.”

"Is that so? Sorry, I forgot."

This was all the man said before turning his attention back to the documents in his folder. He quickened his pace, walking ahead of Kaori and the others. He seemed quite busy, or perhaps his interests didn’t align with high school students armed with cameras.

With Ayase’s introduction, she whispered, “He’s not very interested in humans.”

Following the signs out of the corridor, fluffy jellyfish started appearing one after another in front of them. They had entered Hall B. Ahead, a crowd gathered, and the straightforward call from an elementary student rang out: “Shark! Shark!”

The shark tank? There it was!

Though their hearts brimmed with anticipation, Midorikawa and Ayase headed directly into the shadowy corridor beside the tank, leaving the reporters crestfallen as they followed behind. At the corridor’s end, there was a door.

“Beyond here is what we call the ‘backstage’. The director’s office, the keepers’ room, etc., are inside.”

While Midorikawa unlocked a code lock, the deputy director introduced them.

On the other side of the door was a mundane corridor lit by fluorescent lights, with the mysterious and romantic blue nowhere to be seen. The lino-covered ground extended straight ahead, presenting a rather dull scene. However, precisely because of this contrast, one could really feel the “backstage” atmosphere vastly different from the exhibition area.

For instance, Kaori noted a round device installed on the ceiling, unsure if it was a smoke alarm or a camera. Whatever it was, since this was backstage, it could be installed without embellishment here.

On the right-hand side were signs for rooms: "Equipment Room," "Supplies Warehouse"... At the end was a double door, with corridors extending left and right and stairs leading down and up on the right.

There, the two staff parted ways. Midorikawa turned to the left corridor, and Ayase headed for the stairs. The doctor, before leaving, told the deputy director, “Please inform Mr. Daitabashi to come to the medical room.”

She agreed, then turned back to introduce to Kaori and the others:

"The underground is the filtration pool, and the director's office is on the second floor."

Kaori and the others were about to follow Ayase upstairs when, behind them, the door labeled "Supplies Warehouse" opened, and a girl emerged.

At least in Kaori’s eyes, she was indeed a “girl.” She was about the same height as Kaori, maybe a bit shorter, with an innocent face. Without her keeper's yellow Polo shirt, she could easily be mistaken for another high school student interviewer.

A cute bun head with sleepy eyes. Although the towel tucked in her belt was similar to other keepers’, she held no bucket, only a yellow-handled mop and a bucket for mopping.

“Ah, Ayase Sis… Hello there!”

“Honoka, you’ve worked hard. Cleaning?”

“Yes.”

Named Honoka, she started upstairs. She caught Kaori’s eyes for a moment, and they nodded in acknowledgment.

“You’re from the high school newspaper…?”

“Yes, we’re from Kazekozan Newspaper. So you are... a staff member?”

“This is the part-timer, Honoka Nishikawa. She's a student at the Oceanic University, whom we invite only in summer," Ayase informed them.

“Oh, a university girl… Unexpected.”

“Little Ike, watch how you speak.”

Kaori chastised the high-schooler who seemed no more than a child himself. After climbing one flight, Honoka nodded awkwardly in farewell, saying, “I’ll be going now.” In that instant, Kaori noticed the childish Mickey Mouse watch on her slender wrist.

After this brief encounter, Kaori and the others walked along the corridor. Passing by doors with small windows labeled “Conference Room One” and a password-locked “Men’s Locker Room,” the backstage silence was soon disrupted by chatter.

“Funami, please do the financial records. Funami!”

“That’s right, isn’t it? So, the move should be immediate upon danger!”

“That I know, but why tell me? You need to consult the doctor first.”

“Did anyone see the USB I left here?”

“Shibaura, I finished the logs, and last week's report is done too.”

“I could really use a coffee. Mizuhara, could you make one for me?”

“Don’t joke, the USB must be found first…”

“Funami!”

Voices came from behind four open doors. According to Ayase, “Ahead is the keepers' room, and beyond it is the office.” They halted at the entrance to the first keeper's room.

Inside the spacious room were about twenty desks. Filing cabinets lined the walls, with a copier in between. Each desk had a computer, a small file rack, a pen holder, and chaotic piles of documents creating a mountain. Based on her experience, Kaori thought this resembled the “staff office” at school. No, it was a room for aquarium staff, naturally resembling a staff office.

Unlike school, though, the office workers uniformly wore yellow T-shirts, and towels, rubber gloves, and buckets mingled among the documents. There was also the serene blue vista of Yokohama Bay outside the window—those were the differences.

Four keepers worked inside. There was a stalwart auntie and a commanding uncle, and there was an elder with a face full of wrinkles, and a short-haired youth. Though few in number, they were all busy enough to dazzle an observer. The most eye-catching, however, was the auntie.

“Funami! Financial records!”

Auntie poked her head out through another exit and shouted to the adjoining office with even more volume. A lackadaisical voice responded from next door: “Oh—”

“Oh dear… Ah, Ayase-miss.”

Noticing the company in the corridor, she walked over through the keepers' room. Her voice was boisterous, but her expression was gentle and friendly, and Kaori mentally nicknamed her “Bold Mom.”

“These kids are from the newspaper club?”

“Yes, they’re from Kazekozan High. This is the head keeper, Ms. Izumi.”

Following Ayase's introduction, the auntie—Izumi—smiled at Kaori and company and said, “Nice to meet you.”
"It's quite rare for a high school newspaper team to come and interview in a place like this," someone remarked.

"Yes, that's because we have a unique style..." Kaori was about to seize this opportunity to promote the Kaze Hill Times, but her words were drowned out by a deep voice coming from behind Izumi. The voice said, "I don't agree with letting outsiders in." The speaker was a man about fifty years old, with arms crossed over his chest, frowning at them. He was burly and muscular, making his polo shirt appear tight.

"Moreover, it's just a group of high school brats. I don't know what the director is thinking..." He said this without any regard for the presence of the people in question, causing Kaori to frown. Even putting aside Ikezumi’s youthful appearance, calling both herself and Kuramachi 'brats' was truly unexpected. How dare this jerk speak in such a way!

Izumi chided, "Don't say that," but the man seemed uninterested in changing his views, and continued to frown as he addressed Ayase, "By the way, Ms. Ayase, have you seen Dr. Midorikawa?"

"Oh, I saw him earlier. He should be in the medical room downstairs."

"I see. Just in time, I need to discuss the clownfish with him..."

"The doctor also asked me to bring you along."

It seemed that the man was indeed the Daitabashi Midorikawa had mentioned. This assumption was soon confirmed. A short-haired young man from the depths of the room said to him, "Mr. Daitabashi, please check the log." Ending his conversation with Ayase, Daitabashi walked toward the young man. As he glanced back at the group for a moment, his eyes still bore hostility towards the 'brats.'

At that moment, a tall man came over from the office. "Ah, Funami, you're finally here. These are the financial records for you."

Izumi handed him a stack of documents. The man, referred to as Funami, listlessly accepted them, saying, "Sorry for the bother every time."

"Don't spill coffee on them again."

"Don't worry, I've learned my lesson... Oh, are these the kids here for the interview? I'm Funami, responsible for the finances. Pleased to meet you—"

He introduced himself warmly, showing he supported the 'kids.' Around forty years old, in a wrinkled shirt and scruffy beard, he appeared somewhat unreliable. And he was in charge of finances. Isn't finance supposed to be important? Can he handle it?

Of course, Kaori displayed no noticeable reaction. She smiled and stretched her words in response, "Nice to meet you—" Meanwhile, Ayase and Izumi continued their conversation beside them.

"The director is still in his room, right?"

"Yes, he should be. Oh, by the way, Mr. Fukamori mentioned that the pipes in the shark tank need repair. Could you let the director know?"

"Alright, I'll pass it on... So, Ms. Sakasaka, could you wait here for a bit? I'll head to the director's office."

Ayase gestured further inside past the office, probably indicating the director's office. Kaori was about to agree when she suddenly remembered something important: "Um..."

"Excuse me!"

Before Kaori could call Ayase back, she was interrupted by the sudden outburst of Kuramachi, who raised his hand abruptly. He looked desperate, so Kaori held her tongue. Ignoring the gentleman's priority, the vice president said, "Can I use the bathroom..."

"Huh? Kuramachi, you're getting upset at a time like this?"

"What's the difference? I'm just nervous..."

"You shouldn't hold in what needs to be released, young man!" Funami, who was confirming documents while leaning against the wall of the keepers’ room, commented. Izumi poked him, saying, "Don't say such unrefined things!"

Ayase smiled, "At the end, turn left and head inwards to find the bathroom."

"Sorry, I'll be right back." Having learned the location, Kuramachi immediately jogged there, his pale forehead dripping with sweat. Kaori then remembered that since Ayase had started leading the way, Kuramachi had hardly spoken a word. He was likely in severe pain from stomach cramps all along.

"He's unwell, perhaps stomach pains are the culprit," Kaori whispered to Ikezumi.

"Kurmachi has always been like this. No, it’s the president who’s overly excited."

"Hmph, and wasn’t Ikezumi just as excited about the 'dolphin performance'?"

"Then what was it you wanted to say, Ms. Sakasaka?" Ayase turned back and asked Kaori, noticing she had called her. Truly worthy of someone who described herself as a secretary.

"Well, if possible, I’d like to get permission to take some photos."

"Photos? Of this place?"

"Yes, I want to use them in the report."

Her words were partly true. The photos were indeed for the report, but her personal desire was more pressing. She wished to capture the precious behind-the-scenes of the aquarium in pictures.

Ayase pondered for a moment, muttering to herself, "Hmm, alright," and then said, "There isn’t anything here that can't be photographed, taking two or three shots should be okay."

"Really? Thank you!"

"No need to thank me, it’s fine." Perhaps her overly enthusiastic gratitude amused Ayase, as she chuckled and headed down the corridor. Funami, who had finished confirming the documents, also left the keepers’ room, humming as he returned to the office. Izumi was already back at her seat at some point.

Alright! Kaori and Ikezumi nodded to each other. Ikezumi also prepared a digital camera for the task. They entered the keepers’ room and pressed the shutter without worrying much about what they captured. The limit of two or three shots that Ayase had mentioned was quickly exceeded, but as long as they didn't speak of it, Ayase wouldn't know.

They took an overall shot centered on the wall to clearly depict the various things in the room, then changed their angle to capture the view of the sea through the window as a background. They snapped a picture of Izumi, with her definitive supervisory demeanor, sitting at the computer. There was a bulletin board on the wall opposite the window with duty rosters and other papers pinned on it; they focused on it—

"Hey, no unauthorized photography!" A sudden shout startled her into pressing the shutter despite the focus not being adjusted. As she removed her face from the viewfinder, she found herself meeting the furious gaze of Daitabashi, veins bulging on his forehead.

"Ah? But the deputy director agreed..." She deliberately emphasized the title "deputy director," leaving Daitabashi momentarily speechless: "…Regardless of permission, it’s still not allowed! We don’t have time for your games..."

"It's fine, it's harmless. Besides, it doesn’t hurt anyone," came a quiet voice to interrupt him.

This time, the interrupter wasn't Izumi, but an elderly man full of wrinkles who had been working at the desk. "But Mr. Shibaura..." 

"They probably want to see how we work, and that's something we should be proud of, right? …Oiso, it's time to prepare the feed, let’s go."

The old man, called Shibaura, glanced at his watch, signaled to the short-haired youth, and struggled to stand. The young man hurriedly placed the documents he was holding on a shelf and picked up the bucket by his feet. His surname was probably Oiso.

"Ladies, please could you let us pass?" Shibaura smiled and asked Kaori and Ikezumi, who were standing by the door. Realizing this, they promptly stepped aside, to which Shibaura gave a gentlemanly nod of thanks. Despite having skinny arms with visible veins and deep forehead wrinkles indicating his age, he remained robust and seemed determined to work for the rest of his life.

Kaori suddenly felt the urge to say something to him. Perhaps a word of thanks for his help. But doing so in front of Daitabashi might be antagonistic. If she were to remark on his vitality despite his age, that might be impolite to Shibaura. After some consideration, she uttered, "Everyone must be busy."

"Indeed, with our limited manpower. I've been here for nearly forty years, and it's always been like this," Shibaura replied cheerfully as he and his stern-looking partner headed towards the stairs, the towel at his waist swaying with his steps. Forty years of continuous work meant that he had been at the "Marumi Aquarium" since its founding. It was no wonder Daitabashi did not dare contradict him.

As they watched Shibaura and his young companion depart with reverence, another pair approached from below, heading up the stairs in the opposite direction. Both were young and seemed somewhat familiar. They appeared to be zookeepers, wearing matching yellow polo shirts with towels at their waists. They looked fit and had a dark tan, almost like a well-matched couple.

"Oh, little ones. Lost your way?" The man asked while staring at Kaori and the others. He probably mistook Kaori and Ikezumi for siblings. But upon seeing the camera, he quickly added with a smile, "I'm just kidding. You're from the newspaper club, right? Feel free to come to the dolphin show later. The lady here and I will both perform."

"Amamiya, you're exaggerating again…" The woman with him seemed exasperated, to which the man repeatedly explained, "I'm kidding," and headed into the keepers’ room. Only then did Kaori remember that they were the two waving in the poster for the dolphin show at the pool.

"Oh, Amamiya, Takino, thanks for your hard work," Izumi raised her head from the computer and said in a loud voice. They replied, "Thank you for your hard work," indicating the man was called Amamiya and the woman was called Takino.

"How's the condition of Rufi?" Izumi inquired with a raised voice.

"The condition is good. After all, it's been growing in the aquarium since the third generation, and it’s not afraid of people," Amamiya, slanting against a shelf by Izumi’s desk, remarked. On closer inspection, now that it was known he was responsible for the dolphin show, Amamiya indeed didn't seem like a weak man. His arms possessed a combination of Shibaura’s slenderness and Oiso’s muscular strength, sturdy and appealing. During their conversation, his right hand occasionally touched his slightly dyed short hair and the protruding watchband. His crossed long legs and the smile at his lips exuded a certain performer-like flair. Kaori discreetly captured him in the frame.

"Its diving skills are progressing well, probably needing another week to learn everything. Even if it can't perform completely, it can play and swim four or five times or just participate in the interaction session."

"I'm not asking about that, I mean its physical condition. Everything okay?"

"Seems fine for now. However, one cannot be lax with Rufi." Takino answered by her desk. Unlike Amamiya’s pretentiousness, she was a lively beauty with a touch of tropical charm. Her hair was tied at the back, and her smooth, full forehead appeared very healthy. Her lower neck seemed un-tanned, probably because she typically wore a seafarer’s shirt.

"President, Rufi is that dolphin, right? The white one on posters and the website?" Ikezumi asked quietly from the side.

"Yes. Seems like it’s going to be part of the performance, although not right now..." Based on what they said, it was currently still in preparation, a real pity. However, because of this, maybe they could publish the newspaper in coordination with its debut, achieving a report with perfectly timed relevance—

"I don't agree." Just as Kaori was imagining her newspaper, Daitabashi admonished the other keepers again: "One shouldn’t force live animals to adapt to our pace, right? The clownfish in the new exhibit has an infectious disease."

"But we need to make the performance more exciting to attract visitors."

"Because we lack any distinctive features," added Takino after Amamiya reiterated the point.

"If the clownfish continues treatment, Rufi is currently the only eye-catcher among our exhibition animals. If Rufi can perform actively in the show, that would attract more attention."

"However... oh dear, look at the time." Daitabashi noticed the clock’s hands had passed 9:40, reverting to a furious demeanor. He grabbed his bucket, stuffed the towel hanging on his chair into his belt, and hastily left the keepers’ room. As he passed Kaori and the others, he threw out, "No photography!"

Kaori's wrath rekindled. She wanted to avenge the snub slightly, trying to snap a picture of Daitabashi’s retreating back as he headed for the stairs, but she failed. Before she could frame the shot, Daitabashi's boxy figure had vanished into the door on that side of the stairs, the sliding door on the right wall.

Kaori then noticed the existence of the door. She quickly stepped over to take a look and saw the sign that read: "B5: Lemon Shark."

This was the "Little Lemon" Amamiya referred to earlier. Featured prominently on the website as "Marumi's Idol," it was the most attention-grabbing shark exhibit in the current Marumi Aquarium. 

Was the tank just behind this door?

Driven by curiosity, she was about to peek inside when someone's voice rang beside her: "No unauthorized access, please."

Kaori quickly turned around and saw a slightly hunched, slender man standing beside her, a meaningful smile on his face.

"Well, typically, the whole back area is off-limits, but since you're already here, maybe it's okay to let you in. No, the tank area is off-limits too. If you go in, they’ll be upset."

"Oh, okay, sorry..."

"No problem at all. You're with the high school newspaper, right? Nice to meet you both. Want some candy?" The man took some candy from his pocket, handing one to each of Kaori and Ikezumi. Though the gesture was like one from an Osaka auntie, his shoulder-length black hair and gray long-sleeve shirt gave him an eerie vibe. He seemed to be in his thirties, neither wearing a logoed T-shirt nor carrying a bucket and towel, indicating he was involved in administrative work like Midorikawa and Funami.

"My surname is Tsu."

"JIN?"

"Like the name of the capital of Mie Prefecture. Tsu, easy to remember, right?" A single-syllable surname, indeed easy to remember.

"Which high school are you from?"

"Fengzhikou."

"Fengzhikou? Hmm, seems like I've heard that name recently..." Tsu said, stroking his chin in thought. Seeing this, Kaori's palms began to sweat.

Back at their high school, a murder had occurred in late June, where a student was stabbed to death on stage in the gymnasium. The shocking news was covered by national media, and once the information was released, the name "Fengzhikou" would not disappear from the subtitles of variety shows for days. Fortunately, the police, with someone's utmost effort, solved the case within two days, quelling the commotion. Yet, the event was likely still fresh in people's minds.

"…Hmm, I can't recall. Anyway, nice to meet you." Thankfully, Tsu seemed not to have connected the dots. Or possibly he did, but chose not to say anything.

She internally breathed a sigh of relief. Tsu passed by Kaori, waved, and walked towards the office.

Were there other clerks? Kaori's curiosity, which had only been half-satisfied, shifted focus. She followed Tsu to near the entrance of the office. Behind her trailed the small-stepping Ikezumi.

They peeked into the room through the open door. It was a bit smaller than the keepers' room and had half as many desks. Perhaps because the clerks didn't need to go back and forth between the office and the tanks, each desk was organized and tidy. It was a rather reassuring room, free of towels, buckets, or rubber gloves. In their place were a bookshelf and a coffee machine between the copier, resembling an office in some business building.

Besides Tsu, there were only two people in the room. Funami continued lazily checking files, and a thirty-something woman with a head of curls and glasses. She was wearing a T-shirt with artistic fonts, meticulously sorting through the small items on her desk. Her attire and behavior both exuded an assertive drive.

"Tsu, weren’t you arranging moving stuff at the new exhibit? Finished already?" Funami asked, noticing Tsu's return.

"Fukamori knows more, so I left it to him."

"Huh? You slacked off, huh, making things difficult once again." Though Funami said it with a bitter smile, he didn’t seem too troubled. The woman searching through her desk drawers lifted her head and quickly asked, "Hey, Tsu, do you know where my USB stick is?"

"USB?" 

"The one in red."
"I clearly put it here, but where did it run off to?"

"Is this it?" Tsutou took a red USB stick out of his pocket and tossed it to the woman.

"Oh, this is it. How did it end up with you? Don't just take other people's things!"

"No, Amamiya said if you want someone you like to notice you, just steal something."

"What kind of logic is that, like a school kid... then let me ask you, do you like me?"

"Like you? Mizuhara, how could that be? The USB stick was accidentally stuck between some files."

"What are you doing?!"

"Mizuhara, can you make me a cup of coffee?"

"Funami, just hold on for a second!"

Things were chaotic on this side too. Kaori quietly entered the room and took some photos of the office.

"Is it okay to take pictures like this?" The criticism came from a calm voice behind her, but she wasn't startled this time, as the voice was all too familiar. She slowly turned around and saw Kuramachi coming back from the bathroom.

"Yeah, it's fine. I've got permission. How's your stomach, Kuramachi?"

"It's fine now."

She wanted to make fun of him, but he replied so nonchalantly. Such a boring vice president.

"Even if you take photos here, they probably won't be used in the report, right?"

"I just wanted to take photos for myself, even if they're not used."

"Abuse of power... oh well, I won't argue with you. Has the deputy director not returned yet?"

"No, but soon... ah, here she comes."

The door next to the office opened, and Ayase walked out.

"Sorry to keep you waiting. The director's work got held up a bit."

"No worries, we enjoyed waiting."

Kaori's response was true. With staff appearing one after another, such an interview scene was fascinating to watch.

Ayase leaned against the corridor wall, and a man appeared from the door behind her.

"Let me introduce, this is the director of Marumi Aquarium, Director Nishinozu."

The man glanced at the school newspaper club members and immediately smiled, "Hello, hello! Thank you for visiting us today!"

*

"Thank you all for coming today. Now, the four-school league officially begins!"

Our advisor, Masumura’s voice echoed throughout the gym. After a fifteen-minute delay, the mini-opening ceremony finally commenced.

"This year's program is the same as previous years. The morning will be individual elimination matches, and in the afternoon, we'll have inter-school league matches with the official members. Please take care of that! With the hot weather, please remember to stay hydrated. Turn right as you leave, and there are vending machines outside the cafeteria. There are restrooms behind the stage and in the school building..."

Yuzuno absentmindedly listened to the announcement about the various cautions at Kazekozan. She knew better than anyone where the vending machines were at her own school, and there were other things that worried her more. Yuzuno's attention, or perhaps everyone's attention, was focused on the person who suddenly appeared on the field.

"Well, the elimination matches will begin in ten minutes. Before then, each school is free to hold meetings and warm-up."

As soon as the words were finished, the lined-up girls dispersed according to their schools, further adding to the colorful hues of the gym with a fourth color. Blue, white, black, and red. A fiery shade of crimson.

"Not good, not good, this is not good."

As soon as the chat ban was lifted, Sanae started mumbling like a spell:

"Why is Hiten's ace, Shinjiritsu, here... not good, really not good."

"You don't need to say it; I already knew it’s bad!" Yuzuno said, but her gaze was similarly fixated on the fourth color — the crimson group, especially their central figure. She was surrounded by her juniors, who were noisily crowding around her.

"Senior Shinjiritsu, please have a drink."

"Oh, thank you!"

Wow!

"Senior, I'll hold your watch."

"No need, it's fine. It's not an official match."

Ah!

No matter what she said, her juniors responded enthusiastically, as if dedicating themselves to her was the greatest joy. Whether it was her treatment or their responses, they reflected her popularity comparable to an idol.

Whether everyone treated her this way because of her strength, beauty, or talent was unknown. In any case, Yuzuno and Kaori muttered with pale faces:

"This, this is truly a different world..."

Choko Shinjiritsu.

Hiten Academy was already a perennial champion. And she, only in her second year, had been honored as their ace. She was adept at left-handed defense, with a playing style as flexible as a whip, unquestionably the strongest in the county. She dominated in Kanto and even held a place in the national rankings. She was a flawless top-tier player.

An unreachable existence — yet, she still had some connection with Kazekozan. Specifically, it was her relation to Kazekozan's Captain Sugawa. Hiten's ace, who viewed Captain Sugawa as a rival, was this very Shinjiritsu. They had met twice in singles semifinals and quarterfinals, with Sugawa painfully falling short of victory in last year's rookie match and this year’s Kanto qualifiers, often losing midway to Shinjiritsu.

Logically, the one who should view the other as a must-defeat rival should be Sugawa. However, for some reason, their relationship was entirely reversed. After securing entry into the Kanto tournament, Shinjiritsu accepted an interview with a table tennis magazine, where she discussed her enthusiasm and commented, "No problem. I will definitely win in Kanto too. Because the only one who could probably beat me in Kanto is Kazekozan High School's Nao Sugawa."

Her tone was exceedingly arrogant. That alone was one thing, but what puzzled the reporter was that although Nao Sugawa was known for her strength in the county, she wasn't quite at the level to contend with a national player like Shinjiritsu. When pressed for further reasons, she responded:

"It's a matter of feel; you don’t sense it unless you actually face her. Anyway, I admire her a lot."

Hence, in Shinjiritsu's personal view, Captain Sugawa became her strongest adversary in Kanto purely due to a "sense." Although Yuzuno and the others were completely clueless about the real cause, this report filled them with pride.

Come to think of it, perhaps the moment Yuzuno learned of Shinjiritsu's statement was when Sugawa became an idol of admiration to her——

"Sa, Ka, Wa, Na, O!"

The voice, which was previously cajoling the juniors, now distinctly called out the name of Yuzuno's idol captain. Choko Shinjiritsu left the Hiten group and headed directly towards Kazekozan.

Sanae seemed overawed by her presence, hiding behind Yuzuno. Indeed, her bearing exuded an aura beyond ordinary.

Her beautiful gait, confident smile. The two legs exposed beneath her uniform were without a trace of fat, just like a model's. Her glossy black hair was tied at the back, and her features possessed a neutral beauty. Yuzuno felt she could somewhat grasp why the juniors respected her so.

The team members stepped aside, making way. Shinjiritsu calmly walked down the path to stand before Sugawa. The two were similar in height and build. The blue that mimicked flowing lines and the red that mimicked the crimson sky complemented each other. Only their uniforms were unmatched.

"It's been a while, hasn't it?"

"Yes, it has. How have you been?"

Sugawa replied easily, as if talking to a friend.

"Great, couldn't be better! What about you? Oh, I read in the news that there was a case at this gymnasium. Is everything alright?"

"Don't worry, a talented detective solved it quickly."

"…detective? Not the police?" Shinjiritsu tilted her head in confusion.

Sugawa shrugged and switched topics, saying, "But you did surprise me a little. I thought you weren't coming. Weren’t you in Kyoto?"

"Oh, I was in Kyoto. I just took the bullet train back."

"…why come back?"

"Do you have to ask?" Shinjiritsu stepped closer to Sugawa and said:

"To have a match with you."

Woah—

The surrounding Kazekozan team members couldn't help but exclaim softly. It seemed Shinjiritsu truly viewed Sugawa as a rival.

"You ran out of national league training camp just for this?"

"It's fine. We have a break this morning. In other words, this is my personal matter. I personally want a match with you, satisfied, I’ll head back."

"The morning is an elimination match."

"It doesn’t matter. I won't lose. At this level, you can win too, right? As long as neither of us loses, there will be a chance to play against each other."

"…I'm honored, but why do you want to compete with me?"

"You can win, right?" — Sugawa didn't answer the question but posed another.

"There are mismatches in playing styles, you know. I believe the two of us are the most mismatched. Playing against a difficult opponent helps identify one’s weak points, a great training."

Mismatched. Indeed, Shinjiritsu’s chop-focused defense and Sugawa’s fast attack were diametrically opposed in tactics. However, similarly styled players were numerous; it must still be a matter of feeling.

"…besides, the gap between you and me isn’t as wide as you say. Hey, don't you agree?" Shinjiritsu suddenly posed a question to Yuzuno, who was nervously listening on the sidelines. "Well, um, um," Yuzuno stammered in reply, "Yeah, I think Sugawa is really, really strong."

"You see, I told you."

"Even if she says that, I still don't compare to Shinjiritsu."

"Then, if you were to compete with me, would you lose?"

"…Well, if I were to match up with you, I'd approach it with the belief I’d win."

Oh—oh—oh—! The commotion grew louder. Captain Sugawa was no less imposing. Joyful, Shinjiritsu laughed, "That’s the spirit. Then I'll be waiting for you."

She gracefully waved and returned to the Hiten seats. Her juniors once again greeted her with cheers and loud support.

Sugawa watched her retreat, then whispered to Yuzuno, "Shinjiritsu is amazing, but what a peculiar person."

"Something amazing about Sugawa is that you remain unfazed against someone like Shinjiritsu..."

Huh? Really? — Sugawa seemed to realize it only there.

"Yes, maybe because that case hardened me?"

Back in June, during the murder case at the gym, Sugawa was mistakenly thought to be the culprit and interrogated by a county police detective. Indeed, compared to that, any pressure was a trifle...

"Ah, that’s right. Hakamata, thank you!"

"Hmm?"

"Because you said I was strong, just now."

"Oh, why thank me for something like that. I was only stating the truth."

Her reply was again stuttering. Even though Sugawa was just thanking her, why did her mood become so unsteady, and why were her cheeks beginning to heat? When she didn't know what to do, Masumura approached carrying a stack of papers, saving her.

"Come and look, here's the schedule for the morning's elimination match."

The players each took an A4 printout paper passed from person to person. It was a singles competition, mixing grades and schools. The names of roughly 50 contestants were divided into two halves on it. With not too many people, seeded players were evenly distributed throughout.

Yuzuno, calming herself down, found her name— "Yuzuno Hakata (Kazekozan 1)" —in a pretty far-off spot, in the sixteenth match. Though it would take some time before it was her turn, her match-up seemed favorable. The first-round opponent was a first-year from Toukishi High, and although the second-round opponent would be against a seeded player, the name "Haruko Saku (Sou 2)" was penciled on the sheet, indicating they might not be present. Meaning, she'd win by default in the second round; if she could defeat her first-year opponent in the first round, she would proceed to the third round.

"Yuzuno, how about yours?"

"It's good, awesome, a chance to make it to the third round."

Yuzuno pointed at the part showing the seeded player’s absence to Sanae. Sanae’s envy was evident— it seemed she wasn't as lucky with her draw.

"That's great! Win the third round, and you make the top eight, no elimination!"

"Yeah, I’ll do my best to give it a try..."

Maybe she could stand on equal footing with Hiten and Sugawa someday. As she indulged in her fantasies, Masumura, like during regular meetings, raised his hand and summoned the players:

"Everyone, take note. As you may know already, Hiten’s Shinjiritsu will parachute into the competition. There was no spare slot in the elimination matches, but conveniently, there’s one absence, so we'll place Shinjiritsu into that slot. Please mark it in your notes."

That's right, she’d come today suddenly, and the elimination match-ups were already arranged, so there was no slot. Even if she made the effort to come from Kyoto, if there was no spare slot, she couldn’t face off against Captain Sugawa. Luckily, one spot was vacant; she got lucky.

"Hmm, absence... one person...?"

"Oh, in the lower right corner, the second round of sixteenth match, Saku. It’s penciled out, see? Please add Shinjiritsu to this position. Now, everyone, do your best!”

As Masumura finished organizing things, he walked towards the committee chairs set up in front of the stage. Yuzuno, holding the elimination match sheet, became stiff. Only her fingers were trembling slightly.

"Wh- Wh- What..."

The opponent in the second-round match that Yuzuno was originally supposed to face was Saku. That means—

"Y- Yuzuno, it’s okay..."

Sanae's voice suddenly seemed so distant. Thus, in Yuzuno Hakata's second-round match, she would face Choko Shinjiritsu.

3 Yokohama’s Shark: The Panic Caused by a Corpse

Director Masahiko Nishinozu of Marumi Aquarium had a loud voice, a bright smile, was short in height but wide, an elegant yet approachable figure.

"Your name must be Kaori Sakasaka, nice to meet you!"

As he exchanged cards with Kaori (her second successful card exchange), he bowed continuously. His attitude was even more polite than Ayase and the elder Shibaura.

He appeared to be between fifty-five and sixty, with his rounded, keen eyes surrounded by fine lines, and his beard was neatly maintained. He seemed more like a circus director than a director of an aquarium. Casually dressed in a short-sleeved T-shirt, he didn’t wear a tie. However, a tailcoat and tall hat may have suited him too.

If everything proceeded smoothly from here, his impeccable director image would likely persist to the end, but—

"Director! Could we swap a new printer for the control room?"

Mizuhara stuck her permed head out into the corridor, asking persistently.

"Huh? Ask Funami for this kind of stuff."

"Funami works too slowly!"

"My work is slow, sorry for that." Funami, holding a paper cup, said while sitting on the office desk. It seems he eventually went to make the coffee himself.

"Please! The printouts are all fuzzy. It’s still time to order from the vendor now."

"Alright, alright, I’ll arrange it."

Perhaps hearing his voice, Izumi, Takino, Amamiya, and others stuck their heads out from the caretakers’ room entrance and said, "Oh, Director, about those shark tank pipes from Fukamori..."

"Got it, Ayase has informed me."

"Director, Ruffy, if we leave only a week's training, wouldn't it be a bit..."

"Alright, got it, we'll discuss this later."

He nodded repeatedly, his hairline shaking as he responded to the staff's issues. It seemed he, too, was besieged by work pressures.

"He’s such an adventurous old boy."

Someone commented behind Kaori. She turned to find it was Amamiya, his elegant face breaking into a mischievous child-like grin.

"Please humor him appropriately."

"So, he’s an adventurous old boy..."

Director Nishinozu coughed twice, returned his commanding presence to his expression, and said smilingly, "Now, shall we head to the director's office."

Kaori observed, thinking: "Beautiful analogy!"

—Sakasaka, are you ready?

—Yes, good to go— Ikezumi, how about you? Are you alright?

—No problem, no problem, I turned on the device earlier, and it's recording right now."
— Alright, let's try that again... Thank you so much for giving us permission to conduct this interview today!

— No problem at all; I should be the one saying thank you. Our aquarium is quite humble, so it's rare for a newspaper to come interview us.

— Although we're just a school newspaper club, a high school extracurricular activity... Anyway, we appreciate your cooperation today! We'll be conducting a small interview on the attractions of the aquarium, starting now. I'm Kuramachi, the vice president.

— I'm Nishinozu, pleased to meet you. Haha, I'm feeling a bit nervous.

— No worries, no worries, we won't ask particularly serious questions... Uh, this is President Sakasaka, in charge of photography. Over there preparing notes and recordings is our junior...

— Ah, where's the log gone? Really strange.

— That's Junior Ikezumi. The one who just spoke was Ms. Izumi, right?

— I think so... Oh, sorry, was my voice recorded?

— Possibly... it's in the recording. But it's alright. Senior Kuramachi, please continue!

— Well, I'll start with the questions then. First, the usual one: What makes Marumi Aquarium charming?

— Hmm... As I mentioned, we're a modest aquarium, but that's exactly why people can visit easily as it's close to Yokohama Station, especially during summer vacations...

— Hey, Tsutsu, where are you going? Hurry up with your work, seriously!

— That's the charm... That was Mizuhara just now.

— Um, Mr. Nishinozu, Senior, sorry for the interruption! That part might be problematic; can we redo it?

— Oh, okay, okay. Sorry about that, it's a bit chaotic. Ayase, could you remind them?

— Ah, no worries, it's fine, really. So, please continue talking about Marumi's charm...

— Hey, Takino, do you know where the log is? Huh? Where's the dog whistle? How would I know!

— Ikezumi, right? Please pause for a moment. 

With a beep, the recording stopped. The recorder was a quality one, capable of recording for six hours straight, but the display showed only two minutes so far.

“Sorry, our staff tend to be quite loud,” Nishinozu apologized with a wry smile, while the hearty voices of Izumi and other staff could be heard clearly from the other side of the door.

The director's office was small, with a set of sofas and a coffee table for receiving guests near the door, and two desks further inside, with a file cabinet against the wall. The only notable item was a small microphone in the corner used for internal announcements. Kaori and the director sat face to face on the black leather sofas, while Ayase sat at a desk, watching them. It seemed like this was the deputy director's office.

The director glanced menacingly at the thin wall and suggested, “The place isn't great. How about we move to another room?”

“Oh, right. If it's okay, we won't be shy about it.”

This time, even Kuramachi wasn't shy. Whoever thought it, the better the recording environment, the ideal. 

“Where shall we go? The meeting room next door... That won't do, Izumi's voice may still be heard there.”

“Perhaps the exhibit area is quieter instead.” 

That was Ayase speaking. Though it might have been a joke, the old man eagerly embraced the idea: “Indeed. If our goal is to introduce the highlights, we might as well conduct the interview with on-site explanations. Everyone, let's do it this way!”

“Huh? Ah... Well, alright.”

The newspaper club members went along with it.

“Hmm, it's now... 9:50. I have about 30 minutes free. Wherever you want to go, I'll take you there. Let's set off!”

Once decided, actions followed swiftly. Nishinozu immediately led Kaori and others out of the director's office. Ayase leaned against her desk, wishing them well with a “Take care”, and didn't move an inch to see them off, appearing well accustomed to such routines. It seemed the director was always this keen.

“Conducting interviews while walking? Will this work?” 

Even Ikezumi seemed to grow anxious, as he pressed the recorder's switch again.

As they were about to pass by the animal care room, Izumi and Takino rushed out. 

“Ah, Director. We can't find last month's care log; do you know where it is? I printed it and put it in a folder, but the folder's empty now. It was just here earlier!”

“Do you know where my dog whistle is? The one tied with a red string. I definitely had it with me a moment ago…”

A head emerged from the more interior men's locker room, featuring a bald spot and a deeply wrinkled forehead. It was Shibaura, who should have gone to the first floor earlier.

“Did anyone see my notebook? I rummaged through my locker and couldn’t find it.”

Coupled with Mizuhara’s USB from before, it seemed like this aquarium had a lot of lost items today. Nishinozu mused to himself, “Today's really odd.” It seemed this wasn't their norm.

“I haven't a clue about any of it. And Izumi, keep your voice down a bit.”

“Huh? What’s that? Was I loud?” 

“Yes, you're being loud right now, in the present tense!” 

That was Mizuhara, stepping out of the office.

“What a noisy workplace!”

She squinted through her glasses, half mumbling to herself and half speaking to Kaori. Though, she herself was quite loud as well.

Mizuhara walked past Kaori and others, then turned right at the corridor before the stairs. Takino, her long hair tied back swaying, followed the same path. Izumi and Shibaura returned to their rooms.

“We should go,” Nishinozu said, and Kaori and the others began walking too. At the entrance of the stairs, looking right, Honoka, the part-time university student, was mopping the floor in the hallway. She seemed to notice them and nodded in greeting once more. Her tightly pursed lips conveyed a sense of duty, appearing very cute.

As Kaori thought they'd be going downstairs, suddenly, she heard a “click” behind her.

All the doors were shut, leaving only the silhouette of Amamiya in the now quiet corridor. He was opening the door to the shark tank’s entrance, preparing to go inside. Earlier, Tsutsu had warned Kaori and others that entry was “prohibited” there. Amamiya was holding a stack of thick documents. What was the dolphin show manager doing in the room housing the shark tank? Although the question flickered through Kaori’s mind, her focus was on keeping up with the continually advancing director, and she didn't voice it.

Passing through a service door, the blue world greeted them once again. Director Nishinozu didn't follow the exhibit order but headed towards Hall A, where Kaori and the others had come from.

As it turned out, the setup of conducting interviews while touring the exhibit areas was a huge success. They took numerous photos with the tanks as the backdrop, suitable for the report. Surrounded by sea creatures and visitors, Nishinozu seemed more aware of his director role, his demeanor, being called by staff constantly, was gone, and he appeared quite cheerful.

He regaled Ikezumi, who extended the recorder, with backstage management tales one after another.

“The seawater we use is brought in from Yokohama Bay. There's a large filtration tank underground. We're adjacent to Yokohama City's water circulation center, and there's collaboration between us. Sometimes, seawater is transported by trucks.

“Our trouble is a lack of staff. Because of the shortage, scheduling is tight, and it’s noisy every day, as you saw earlier. Standing in for others is common, and I'm often bossed around, helping with cleaning floors in the work area and all. Though I was hired as a managing director, I end up cleaning sometimes... Huh? Oh, the work area is the backstage behind the tanks, where preparations and feedings occur. Wasn't there a shark tank door in front of the animal care room? That's the entrance to the work area.

“Having so few people makes us vigilant about theft prevention too. Did you spot the cameras in the first-floor corridors? We use them to monitor all entrances and exits. There was this one time a particularly obsessed aquarium-goer snuck in without permission, stole a keeper's Polo shirt, and took photos of fish before the exhibition—an absolute nuisance.

“There are animals that are only kept backstage in the aquarium. Currently, we're adjusting the blue discus fish, and there are many in the new building. I'll show you later. Oh yes, yes, I need to introduce the highlights, don't I? We organize many small-scale but varied events. There’s a special deep-sea creature exhibition in Hall A right now, featuring many popular species. You know about the dolphin Luffy, right? It's practicing performances and not in the tank. As for Hall B here, first, take a look at these little friends…”

The old man’s machine-gun-like commentary finally paused. The group arrived at a small gallery housing jellyfish aquariums. Now, they could fully enjoy themselves.

In lighting dimmer than other places, jellyfish appeared as if arranged in a painting. The long tentacles of the marrow jellyfish were ethereal and illusory, and the moon jellyfish looked like floating clouds in the sky. Among them, the red jellyfish had red lines truly embedded in their umbrella shapes. The small, adorable blue jellyfish won Kaori's heart at first glance. Their leisurely demeanor was refreshing for the viewers.

“Aren’t they beautiful? We've been raising jellyfish for about twenty years. Currently, we have ten species. The one at the edge is the marrow jellyfish; its tentacles are toxic…”

Nishinozu meticulously introduced each jellyfish. While he claimed to be just an employed director, he was certainly knowledgeable.

After detailing the upside-down jellyfish at the end of the lineup, the director guided them back to the tour route in proper sequence, saying, “There's another highlight in this pavilion.” Kaori was a bit puzzled—weren’t they heading back the way they came via the service door? But she quickly understood Nishinozu’s intent.

Crossing through the service door into the adjoining hall, a massive tank stretched from floor to ceiling. Right now, a crowd gathered before the tank, with children’s joyful shouts cascading one after another.

On the other side of the acrylic, a gigantic shark swam gracefully. Presenting sharks immediately after viewing the soul-soothing jellyfish magnified the impact—a likely deliberate intention by the director. This configuration effectively served its purpose, although anticipating the next exhibit to be sharks, seeing it firsthand was still quite a shock.

Cold, wide eyes, a smooth, gray spindle-shaped body. Whenever it changed direction, its sharply angled tail and fins sliced through the water. The tank had no decorations like reefs—only this immense shark, moving within the deep blue with a kingly presence.

“This is a lemon shark housed here since last year. Sakasaka-san, how do you feel?”

“...It's magnificent.”

Under this overwhelming aura, it was all she could say. Kuramachi quietly exclaimed “Wow—, and Ikezumi was so engrossed that his mouth wouldn’t close.

“It’s 2.7 meters long now and can grow over three meters, so it might get even bigger.”

Even larger than now—that’s even more intimidating.

“The tank was custom-made to suit its size. The water quality is monitored 24/7, and any anomalies alert us through sensors. By the way, do you know where the lemon shark got its name from? It’s a type of real gray shark, and in the wild, they exhibit a lemon-yellow color. But in captivity, as you see here, most turn black…”

Leaving Kuramachi and others as the audience to continue listening to the director, Kaori rushed towards the tank. She set up her DSLR camera amidst tourists raising their smartphones and digital cameras to take pictures. The highly transparent acrylic showed no reflections even from close range, and the scene inside was crystal clear.

Kaori captivatedly snapped away at this majestic figure. She wished the lemon shark would swim nearby, but this capricious model always circled the top of the tank. However, capturing it from below had its own unique artistic composition. She glanced at her digital wristwatch—10:06. The interview and jellyfish commentary had taken longer than expected.

“Wow—,” Ikezumi let out a late reaction of amazement behind her.

“It's so big…”

“Koike, you really could be swallowed whole in one bite!”

“Kuramachi-senpai, don't say such scary things!”

“Haha, don't worry.”

“Lemon sharks are indeed fierce but have rarely attacked humans. Especially in captivity, where they are fed regularly. Even if a diver jumps in, it would likely ignore them unless something major occurs.”

“Oh, I see. Koike, look, that's reassuring.”

“That sure is a relief.”

With a turn, the lemon shark circled back to the upper part of the tank. Kaori tracked its movements with her wide-angle lens.

“However, I’ve often heard of sharks attacking surfers.”

“There are incidents, of course, but worldwide, only a handful occur annually, with fatalities being extremely rare. So, you don’t have to be overly fearful of sharks in any aquarium.”

The shark turned again. An elderly man who seemed like a regular at the aquarium muttered, “It looks kind of strange.” Her digital watch now showed 10:07.

“Sharks eating people is a notion conjured by movies. Unless you dive into its domain covered in blood, it won’t happen…”

Just as the director was saying this, a man suddenly jumped into the tank.

Water splashed, then stilled as buoyancy was achieved, leaving everything silent. Thick acrylic muted all noise.

Everything unfolded on the other side of the acrylic, void of any sense of reality. Instinctively, Kaori pressed the shutter, with her camera emitting a faint click.

The man wore a dirty yellow Polo shirt. His slightly dyed short hair. While his slender wrists were muscular, his limbs were lifeless, floating entirely in the water.

Then, a mist of red seeped from his neck, dispersing into the water.

The man was Amamiya, the zookeeper.

“...Ah!”

Someone screamed.

The shark dove again, quickly darting past Kaori and the others. It then suddenly ascended, maw wide, glistening sharp teeth rushing at Amamiya.

“...Ah!”

A shrill scream echoed, followed by utter chaos.

Children wailed. Couples held hands still, while young women collapsed. Some tried fleeing against the tour route, some stood paralyzed. Kaori was among the latter. She didn't even remember to close her eyes, staring at the unfolding tragedy through the acrylic in a daze.

“Sakasaka!”

Hearing Kuramachi calling her broke the spell, enabling her to move. Turning, she saw the vice president was pale, Ikezumi looked ready to cry.

“Th-this... what on earth is... this...?”

“Mr. Nishinozu, get to the back quickly! We have to save him!”

The stunned Nishinozu was awakened by Kuramachi's shout, dashing toward the service door. Kaori and the others followed suit.

Before the facilities room on the first floor stood Honoka with a mop—it looked like she was cleaning at this spot. She seemed to have heard the screams and anxiously asked, “Director, did something happen?”

“It’s bad! Shark tank... it’s really bad!” 

Nishinozu repeatedly yelled this as he ran up the stairs at the front of the corridor. Still holding her mop, Honoka followed Kaori and the others at the back. The director didn’t rush into the shark tank room immediately but headed straight for the animal care room and office.

“It’s bad! Amamiya, Amamiya’s with the shark... Call the police! Get an ambulance! And make the internal announcement! Quickly call Fukamori!”

The urgency in his voice resounded through the corridor. At Nishinozu’s voice, Mizuhara and Takino appeared at the turn: “What’s going on?”

Kaori hesitated for a moment, pressing ahead of the director to reach the shark tank room door.

Upon entering, she immediately noticed something odd on the floor. Red footprints were left behind on the linoleum.
She avoided the footprints and walked further in, the upper part of the shark tank came into view. The shark devoured its food, causing huge waves on the water's surface.

“Whoa…” Behind her, Honoka made a sound that was hard to distinguish between a moan and a scream.

But what was even more terrifying was the bridge stretching across the center of the tank. At a glance, Kaori involuntarily gasped. Ah, she had felt like this before. Right next to her, someone’s life had been taken. It was a heartbreaking case. Jumping into the whirlpool was already her second time.

She felt unsteady, about to fall… but Kuramachi held her up.

“Sakasaka, take photos!”

“Huh?”

“Take photos! Quickly! Everyone, don’t come directly over here, go around from the right!”

He gave instructions to Mizuhara, Takino, and Honoka, who stood frozen at the entrance. Funami, Tsutou, Ayase, Izumi, Shibaura, Oiso, Dr. Midorikawa, and Daitabashi came rushing one by one. Kuramachi made the same request of them.

The situation above the tank couldn’t possibly be just an accident.

The scene had to be preserved.

Finally grasping the situation, Kaori picked up the camera again and began capturing the footprints on the ground and the condition of the bridge. Ike-san, as requested by Kuramachi, also took out his digital camera while wiping away tears.

The sense of time seemed eternal, yet the digits on the digital watch had just turned to 10:08. The tank sensors that Nishinozu mentioned appeared to detect an abnormal change in water quality, starting to beep an alarm. The exhibition area was even more chaotic, screams could be heard from there. Nishinozu was calling the police with a louder voice than Izumi. Kuramachi yelled desperately to maintain the scene's order, and the overlapping voices of bewilderment, anxiety, and confusion from the staff echoed repeatedly in her head, turning her thoughts into a jumbled mess, making even her own breathing seem frightening.

Only the camera in her hands remained as cold as usual. If she put it down, she might really faint.

To shake off the fear as much as possible, Kaori single-mindedly, continuously pressed the shutter.
第二章 哥哥的调查与妹妹的比赛

1. Sendou and Detective Hakata Return

The parking lot was empty. This was no surprise. Just over an hour after opening, the entire aquarium was closed. Many uninformed visitors would surely come to play, only to end up leaving in tears. It was a disaster for everyone, tourists and staff alike.

Only one section of the parking lot had a few cars parked—familiar black and white designs with "Kanagawa Police" written boldly on them. Under the summer sun, Yusaku Hakata squinted as he drove toward them. Thin clouds and pale blue buildings glided by the left window.

"It's been eight years."

Sendou murmured from the passenger seat.

"I brought my daughters here when they were in elementary school. They were still so cute, not yet in their teens."

"The last time I came was also around eight years ago, with my sister."

"Never would have thought..."

Just as the police car parked next to the patrol car, Sendou fell silent. Although he and Hakata were not yet perfectly attuned, Hakata could guess what Sendou was going to say next.

—Never would have imagined returning under such circumstances.

Opening the door, they were enveloped by the heat. The jacket under his arm proved unnecessary.

"Which way is Building B?"

"Maybe it’s the one over there... or this way?"

They relied on their eight-year-old memories to find their way. People still crowded at the main entrance. Police and aquarium staff in yellow T-shirts explained the situation to disgruntled parents, children, and couples. Above them hovered purple jellyfish images.

The "Welcome to Yokohama Marumi Aquarium" sign was futilely welcoming the detectives.

Rounding the pale blue building, they came upon a wall with many windows and convoluted pipes. Just as they confirmed this to be Building B, two people emerged from a seemingly side entrance—a young man with prominent cheekbones and a middle-aged man in white. They approached directly.

"Excuse me, are you the police inspector from the prefectural office?"

The younger one inquired. Sendou nodded and showed his badge.

"I'm Inspector Sendou from the First Investigation Division, and this is my subordinate, Hakata."

"Thanks for coming. I'm Azusa from the Iso Police Department's Criminal Affairs Division."

He introduced himself with a salute. His hair was curly at the front, and his skin was sun-kissed dark. Perhaps because he worked at a coastal station, he reminded people of a fisherman.

"You arrived just in time."

"We saw you coming from the window, so we came down. It's an honor to meet Inspector Sendou."

"Oh? You know me?"

"I often hear about you from my colleagues in the prefectural police. That high school case, you identified the culprit with just an umbrella."

"Ah, uh, haha."

Sendou's face stiffened at the mention. The high school gym case from June. It was true the police deserved credit, but behind the scenes were all kinds of complex situations. For both of them, it was an unwelcome memory. Hakata coughed to change the subject:

"So, the scene is inside this building?"

"Yes, on the second floor of the shark tank. The forensics team is examining the scene. The relevant people are waiting in the meeting room."

"Waiting? For questioning?"

"We just did a brief inquiry. Everyone is busy with work..."

Azusa glanced back. At the open roller door of a wide loading area, a truck was slowly moving out in time with the investigator's signals.

"What is that?"

"The shark."

The man in white, who had been silent until now, spoke tersely. A square-faced, cold expression. It was the forensic expert, Kuninaga.

"Mr. Kuninaga, long time no see."

"Not since the gym case."

Ah, the gym again. Now even Hakata's expression turned rigid.

"Um, the shark, it can’t possibly be..."

"You’ve probably heard the overview of the case. We had to put the man-eating shark to sleep, then load it into the truck."

"It took thirty minutes to secure the scene and calm the shark, thirty minutes to remove it from the tank, and another thirty minutes to load it into the container and put it on the truck... Investigators and all staff involved worked hard, both inside and outside of their duties."

The focal point of the investigation, the truck, moved past them. Hakata checked the time: 11:45. The incident occurred after 10, so the battle with the huge shark had lasted an hour and a half. He offered heartfelt sympathy, "That must have been tough."

Kuninaga crossed his arms and said, "Next, we're going to perform a dissection. We could use the veterinarian here, but he's now a suspect. So we're arranging experts from the Marine University and Hakkeijima to assist."

"So, the victim really is..."

"He was eaten from the abdomen up."

The forensic expert said calmly.

"I've examined countless drowning victims, but this time it's different. We don't even know if the body in the shark's stomach is intact."

First dissect the shark, then dissect the victim retrieved from its stomach—

"Ugh..."

The very thought made Hakata cover his mouth involuntarily. Thank goodness he hadn't eaten lunch. Veteran Sendou was unfazed, nodding to Kuninaga, "That's tough, but I'm counting on you."

"I'll do my best. But don't expect too much from the results. After all, a case where someone was eaten by a shark on land... It's my first encounter."

Leaving those words, the forensic expert strode off toward the loading area.

"...It's a first for me too."

Sendou muttered quietly to his back.

A bead of sweat slid down his cheek. Not just from the summer heat.

*

About an hour earlier.

Yuzuno knew the sensation on her cheeks. Maybe not just from the heat, but also from nerves. She wiped her cheeks, flinging off the sweat, leaned forward, and focused on her opponent's toss.

Thud—

The first serve hit the net, a redo. She knew her opponent was also nervous. The second serve succeeded, though less aggressive perhaps out of fear of making a mistake. Returning it was easy, and she hit it back. When the ball struck the back of the paddle, she saw the opportunity to counter. The ball bounced nimbly off her side of the table, drawing a large arc, spinning slowly.

Now's the time to strike.

This desire drove her. Yuzuno jumped toward the ball, swinging her paddle with all her might. Despite an awkward style, the smash was decent.

"Good shot!"

She didn't victoriously and loudly celebrate but gripped the chest of her uniform with her left hand, letting out a soft cheer. It was Yuzuno's unique cry of victory. When she first started playing table tennis in junior high, she was always anxious on the court, praying as if to deities, pressing her hand against her chest to calm her nerves. This habit remained and had become her unique way. A negative legacy, really, and made the front of her clothes creased, so she tried to change it without success.

Anyway, she scored. As her first match was self-officiated, Yuzuno flipped the score while her opponent fetched the ball. The score was now 7-10.

Yuzuno's match point.

The knockout tournament was a best of three format; both she and her opponent, a first-year from Tang College named Matoba, had won one game each, making this the deciding round. One more point, and Yuzuno would secure the victory.

Matoba had a gallant look, slightly boyish, and was about Yuzuno's equal in skill. Though she had led throughout, the margin was only three points—carelessness wasn't an option.

Pressed to the edge, Matoba's second serve. She attacked aggressively, hitting a spinning ball from the start. The ping pong ball accelerated upon bouncing, and Yuzuno barely managed to catch it. In terms of spinning technique, Matoba had the upper hand. Biting her lip, Yuzuno vowed: I can't let you take control!

"Ah!"

Her forced mindset became her downfall. Regret flashed in her mind the moment she swung the paddle. The overfreighted ball easily leapt off the small table, bouncing on the floor.

"Out. 8-10."

Matoba noted, visibly relieved.

Two points away.

Ah—she's closing the gap, what if she catches up? What if it ties, can I still win? Hard to say. Oh no, sweating again. Hot. Can't breathe. Awful, awful, awful; why do I sound like Sanae?

In her simmering mind, thoughts whirled into a vortex. Anxious inside but steady, Yuzuno caught the ball. Turnover serve, her chance now.

—Anyway, I must clear this!

Refocusing, she gripped the four-centimeter ball tightly, adjusted her breath, tossed it, and struck a spin serve. Still slower and less varied than her opponent's, Matoba returned it lightly, allowing Yuzuno to slice hard. Matoba aimed for a wide angle with another spin. Barely keeping pace, Yuzuno realized she'd left a gaping hole on the reverse side. Why had she thought they were evenly matched? It’s clear Matoba was stronger.

Ah, I'm losing—

"Hey!"

A shout broke the tension.

The one who cried out was Matoba.

As with the previous serve, the net blocked her return. The ping pong ball, intercepted, dropped into her court, spinning and skittering with an echo in the air. The match ended abruptly, not fully played out.

Matoba gazed at the ceiling and squeezed out, "Touch net. Match over."

7-11. Overall score 1-2.

Yuzuno won.

"Thanks!" they shook hands, both were sweaty. Matoba had also been at her wit's end. Yuzuno, although matched in skill, had the upper hand in controlling nerves.

"Thank goodness!" Yuzuno again clutched her chest, fist clenched.

The first match, won.

"Yuzuno, did you win?"

As soon as she rejoined her teammates, Sanae asked immediately.

"Yeah, just barely."

"Nice, applause, applause!"

Sanae had beaten a first-year from Chomei as well, so even the way she congratulated was relaxed. Clapping with enthusiasm, she then frowned. "But the problem is..."

"I know, you don't have to say..."

Yuzuno glanced at the red-clad legion from Hiten Academy. Choko Shinjiritsu was busy warming up, stretching her long limbs freely. Her juniors were still as entranced with her as before the match began.

Yes, the problem lay in the next match.

Whether Yuzuno liked it or not, she had to participate. Challenge Hiten's ace, the strongest female table tennis player in Kanto, Shinjiritsu Choko. 

It was as if returning to junior high, unconsciously clutching her chest again. Not to celebrate, but to pray to the divine.

Please let me win this match—or at least don't let me lose too miserably.

After praying, she noticed a clear sweat stain on her chest, from where sweat oozed from her palms.

2. Sea of Blood

Entering through the side door, some of the heat dissipated. Hakata and Sendou retracted their earlier remark, donning their jackets. The corridor, lit by fluorescent lights, stretched forward and sideward. Stairs lay to the left. Perhaps freshly cleaned, a spin mop bucket sat in the corner, with moisture and sheen left on the steps.

"The victim’s name is Shigeru Amamiya, 28 years old. Responsible for caring and performing with dolphins at this aquarium. Height is 180 cm, weight 68 kg. Address is..."

Azusa began briefing them rapidly as they climbed the stairs.

"After the 9 a.m. opening, he and Tomoka Takino, also in charge of dolphins, went to the new building to check the dolphins. Around 9:40, they returned to the keeper's office."

Hakata noted each point in his usual notepad to assist Sendou's thought process later.

"Typically, they would handle administrative tasks and take a break until around 10:20, then prepare for the 11:00 dolphin show. But..."

Upon reaching the top, Azusa paused a few steps down the corridor, stating, "Someone saw Amamiya enter through this door around 9:50."

He tapped at a double door on his left. The sign read “B5 · Lemon Shark.”

"This is a shark tank?"

"Yes, staff feed and clean in this space, aka the keeper's work zone. Odd, as the dolphin caretaker, he came here, carrying feeding logs—a behavior unlike his norm today."

Azusa pushed wide the door across from them, on the right of the corridor. It read "First Meeting Room," its simple setup hinted it had become a temporary base for investigators. Piles of investigative material cluttered the table, with forensic techs and detectives from Iso Police hustling about in blue coveralls.

Continuing into the meeting room, Azusa resumed his account. "At that time, several staff were busy with their tasks in the work area. None became suspicious of Amamiya’s absence. About twenty minutes later, at 10:07—"

The detective picked up a stack of photos from the table, handing the top one to Hakata and others.

It seemed to be taken by a visitor gazing at the tank from a gallery below. The photo showed a large shark's white belly gliding through dazzling light. A beautifully composed shot, appearing as though the shark was flying. Yet more ethereal was an intruder inadvertently captured.

A young man in a yellow polo shirt was floating near the shark. No, not floating, sinking. Encased in tiny bubbles, it was evident he'd just entered the water. Not a mermaid, but a merman prince. Although the surface reflected the light, obscuring the view, red blood was vividly visible seeping from his neck, dispersing in the water like mist.

The timestamp at the corner recorded as 10:07.

“A pivotal moment.”

Sendou remarked.

“The actual decisive moment came after. But there are no photos from then...”

“No worries, I know what happened.”

Even without knowing, one could imagine the worst from this image. A bloody man with a nearly three-meter shark—the worst conceivable pairing.

“A ruthless case indeed...”

“Yet conversely, the investigation is straightforward.”

While Hakata worried about the incident's aftermath, his superior voiced the opposite view.

“If someone pushed Amamiya into the tank, such a conspicuous act couldn’t go unnoticed. The investigation on relevant personnel is concluded, right?”

The last query verified with Azusa. He nodded, saying, "During the incident, about one-third of the staff were in the backyard of Building B. There was a minor commotion there too, but thanks to installed security cameras, entry and exit records are clear."
"Security cameras?"

"Huh, you didn't notice? They're right on the ceiling." Sendou raised his voice in surprise beside him.

"I-I'm sorry... I didn't notice."

"Here are the diagrams." Azusa immediately led the two of them into a room. Although this detective appeared carefree, he actually paid close attention to details.

The whiteboard displayed a diagram of the building, with colored magnets placed in various locations. He picked up some spare blue magnets and held them in his hand.

"There are three entrances to this building, which we'll call Building B. First, there's the side door we passed through leading outside. Next is the cargo entrance for trucks, and lastly, a small door leading to the exhibition area. Without the access code, it's generally impossible for people to enter, and all these entrances have cameras installed."

He placed a magnet by each entrance as he introduced them, clearly indicating the locations of the cameras. 

There was one by the outside side door, one on the exhibition side of the corridor door, and one each at the cargo entrance inside and outside—four in total.

"The footage from the cameras is transmitted to the security room of the new building. Investigators have reviewed it at a glance and found no signs of tampering. Furthermore, the camera outside the cargo entrance captured the wall of Building B, confirming that no one entered or exited through the windows. So..." 

Azusa reiterated the conclusion they had stated from the beginning: the entry and exit of people were under full control. 

"From the last sighting of Amamiya at 9:50 to the incident at 10:07, everyone inside the backyard has been accounted for; they were gathered in the second meeting room at the other end of the corridor."

"So, the killer must be among them?"

"Exactly, there's no mistake about it."

Sendou stared at him and asked again, "What about the number of people?"

"Currently, after excluding those who are clearly not able to commit the crime... there are eleven people."

Eleven people. 

This number wasn't small, but for the detectives who expected to deal with potentially hundreds of aquarium visitors, it was quite a relief. Hakata breathed a sigh of relief and wrote down the number "eleven" at the bottom of the page. If they investigated where these people were and what they were doing at the time of the crime, they should be able to further narrow down the suspect pool.

"You all did a good job. As Officer Sendou said, this case seems relatively simple."

"I hope so. I want to solve this as soon as possible and go for some caviar."

"Because of the shark? I'd rather go for shark fin."

"Of all things... Don't relax too much!" Sendou said in a low voice, nudging Hakata. Even though Sendou was the one who made the joke first, at the moment of self-derision, it was clear that he was quite relaxed.

Hakata rubbed his side and his gaze inadvertently fell on a photo on the table—then, he suddenly had a question: "By the way, is there any possibility that the victim committed suicide?"

"Suicide?"

"Even though his neck was bleeding when he fell into the water tank, it doesn't necessarily mean it was murder. Perhaps he cut his own neck and then fell into the water."

Azusa and the other investigators exchanged glances for a moment, then slowly shook their heads, saying, "Hakata, I understand what you're saying, but this is definitely a murder. You can tell just by looking at the scene."

He tapped his finger on the whiteboard. In the center of the area labeled as "above the shark tank", he repeatedly marked with a red pen.

"The scene of the murder is the middle of the bridge over the top of the water tank. The floor is covered in blood; the knife on the floor is evidently not something the victim could have placed, and there are bloody footprints starting from there... Anyway, you should see it for yourself."

He nodded towards the wall along the corridor—behind it was the tank—revealing a fatigued smile from the Iso Police Station detective.

"It's quite something."

The door Amamiya Shigeru passed through two hours ago but never returned from, was now the same door through which Sendou, Hakata, and Azusa entered the zookeepers' working area.

It was a spacious area, with shelves, water pipes, and a few columns along the walls, but no steps or obstructions. Yet, it didn't feel open. There were no windows, the walls and ceiling were exposed concrete, and pipes, ventilation ducts, and crane rails intersected intricately. The dim lighting from the ceiling lamps cast blurred shadows resembling snakes intertwined tightly.

Hakata cross-checked the scene before him with the diagram in his notebook. The zookeepers' working area was a horizontal rectangle located at the center of the backyard. Offices and other rooms surrounded it on three sides.

There were two exits, and they entered through Door "A" in one corner. The room extended diagonally to the right, and along the side was a shallow, dark pool of water known as the "preparation tank". Beyond it, diagonally, was a railing indicating a ventilation shaft on the first floor.

Ahead, the nearest object was a large aluminum rack. Buckets of various sizes were stacked together by category, and there were rubber gloves, boots, towels, brushes, nets, hoses, and other tools for cleaning and taking care of animals. On the left wall was an old locker containing cleaning tools.

In addition to the preparation tank, there was another tank in front of them—the only area bathed in bright light within the dim working area. Normally bustling with aquarium staff, it was now occupied by police forensic personnel.

"That's the shark tank." Azusa pointed to the large pool.

The shark tank—the crime scene.

Hakata was about to move towards the shark tank when he noticed something unusual at his feet and stopped.

The ivory linoleum flooring had turned into a bleak color with a bluish tint. Scattered on the floor were red-black objects.

"These are..."

Footprints.

A trail of bloody footprints extended from the shark tank to here, curving slightly along the wall in the middle, then returning to the original path and extending to their feet. As they moved forward, the color of the blood gradually faded until it was completely gone near the entrance.

"These bloody footprints... could they be left by the killer?"

"Possibly. Does that mean the killer had bloody shoes?"

"If that's the case, it would be easy. But it seems they were one step ahead."

Azusa put on white gloves, approached the aluminum rack in front, and pulled out a pair of slightly oversized rubber boots from the right side where they were placed.

"These are the rubber boots used by staff when working here."

Azusa demonstrated the sole of the boots to everyone. The sole was stained a murky red, with a wavy pattern matching the footprints on the floor. For some reason, there were also white fibrous materials stuck in the grooves of the pattern.

"You're saying the killer was wearing this?"

"Yes, as you can see, the footprints start from the crime scene, certainly attached with blood. The details will be confirmed with a forensic examination, but I estimate this to be the victim's blood. The absorbed paper fibers are also being analyzed and should match the fibers at the scene."

"Paper fibers?"

"Oh, sorry, I haven't explained yet. Besides the bloodstains, there were scattered sheets of logs at the scene... well, it'd be better if you just take a look yourself."

Azusa replaced the boots on the rack and hurriedly gestured towards the shark tank.

However, Sendou interrupted Azusa's action with an uncharacteristically displeased tone, "No, let's save the main course for later." 

Everyone was curious about what Sendou intended to do, but found him bending down to inspect the floor with his face close, retracing the path of the footprints in the opposite direction. With a magnifying glass in hand, he'd resemble Sherlock Holmes. Holding a notebook in one hand, Hakata followed his lead.

"The stride of the footprints is irregular, like those of a drunk."

Upon reevaluation, it was clear the strides varied, some wide, some narrow.

"Is it possible the killer deliberately staggered their steps to conceal their height?"

"Yes, perhaps. They might also have worn oversized boots to obscure the size of their feet. So... hmm?"

Sendou halted his steps where the footprints curved along the wall. There was a small stainless steel-topped basin with a simple pipe, and an about eighty-centimeter-tall narrow mirror on the left. Hakata glanced at the wall and caught a glimpse of half of his body.

The bloody footprints had paused before the basin, with an additional bloodstain on the floor to the right of it.

It was a rectangular shape approximately twenty by thirty centimeters, resembling a giant stamp soaked in red ink pressed firmly on the floor. Small paper fiber pieces were likewise embedded in it, similar to those clinging to the boot soles.

"What kind of mark could this be?"

"That, we don't know. What is certain is, it's not a shoe print."

Sendou turned his attention to the basin and gently twisted the tap, but no water flowed out.

"... Is the water off?"

"They say it's an old building, so the pipes aren't in great condition."

A red stain extended along the basin's stainless steel countertop to the drain, appearing as if water mixed with blood had flowed over it.

"This is the photo taken right after the incident."

The attentive Detective Azusa pulled out a few photos from his chest pocket. These were shots of the area around the pipe from two hours earlier. The water remaining on the sink hadn't dried yet, making the red streaks more prominent. White fibers surrounded the drain and red water splashes marked the sides.

"Did the killer wash something bloody here?"

"Weren't the pipes out of use? Where would the water come from?"

"The remaining moisture on the sink corresponds with the composition of water from the shark tank. It seems the water was fetched from the tank."

"Water from the tank..."

Azusa's detail puzzled Sendou, who flipped to another photo.

The photo was of the floor near the basin. To the right was the rectangular bloodstain seen earlier, while the other side—left of the basin—had—

"...Droplets?"

The picture showed tiny droplets, about a centimeter wide. A single droplet wouldn't raise suspicion but they continued to appear at intervals along the way back to the site, ceasing beyond the basin.

Hakata shifted his view from the photo to the real floor. Though the linoleum flooring was durable, it wasn't highly absorbent. The dried droplets retained their shapes. 

"It seems the killer transported water from the tank from the crime scene to here."

"Assuming the water is related to the case, that explanation would make sense... Detective Azusa, what do you think?"

"The water's composition is just like that in the shark tank. Starting from that location, it's slightly mixed with blood."

Azusa indicated where the footprints began to veer.

"Under normal working conditions, water from the tank wouldn't reach this far. Additionally, not only is the water mixed with blood, it drips in the same path as the footprints. Therefore, I believe this demonstrates the relevance of the droplets to the case."

"What caused that rectangular bloodstain beside the basin?"

"This part remains under investigation. Samples have been collected, results should be ready shortly."

"Hmm..."

Sendou let out a low hum, glanced back at his colleagues. Hakata lifted his head from his notebook after recording details on water droplets and bloodstains. It was proceeding smoothly, as usual.

"Then let's move forward."

Leaving the pipe, Sendou continued to follow the footprints. Aside from the water droplets along the way, some footprints contained white fibers, possibly dropped from the soles.

After advancing about five or six meters, the main attraction—the shark tank—finally confronted the investigation team.

Though now in proximity, Hakata still could only describe the tank in terms like "swimming pool."

As the tank had a subtle curvature, its precise size was unclear. The width and depth were estimated to be over eight meters. Considering the three-meter-long captive animal, the tank's enormity made sense. Nevertheless, it still felt overwhelmingly gigantic. The array of floodlights surrounding the tank continued to illuminate the now ownerless tank. These lights, likewise oversized, created an illusion of reduced stature among onlookers.

A narrow bridge spanned its center, extending towards the far wall, presumably where forensic work had ended. Investigators were lining up to exit, changing from rubber boots to leather shoes upon every egress.

"That's the scene of the murder. The tank was too large, so a bridge was built for operations in the center, colloquially known as 'ma-bridge.'"

"'Ma-bridge'... oh, like the walkway set up in theater ceilings."

Receiving nods from the investigators, Hakata and the others advanced to the entrance to this bridge—'ma-bridge.'

A vision akin to hell.

The path dipped slightly below the linoleum floor, and on this narrow passage, blood flowed profusely to the midpoint. Nearly two hours had elapsed since the incident; yet somehow, the blood had not darkened but remained bright red, merely appearing thinner. It seemed diluted by an excessive quantity of water, delaying coagulation.

Additionally, numerous sheets of paper saturated with blood and water were strewn across the passage, coating the entire entrance area with no gaps. Walking on it softened the paper beneath, leaving footprints like those in snow. Further along, papers were scattered and more trampled, disturbed.

Meanwhile, outside, the tank's water surface reflected a murky brown—likely a result of consuming "food" that bled plentifully and the shutdown of the filtration system, a necessity during investigations.

Under brilliant lights lay the still, noiseless and dark water surface, a blood-covered ma-bridge stretched horizontally across its center, footmarks—a repellent sight—stamping all over. Despite the corpse's removal, the reduction of lurid cinematic hues present, and its partial allure, it remained an unsettlingly artistic when observed by the detectives from the prefectural police department, evoking the world beyond death.

"This is something."

Even the seasoned Sendou couldn’t help but rub his nape in astonishment. He quickly resumed his intense, focused demeanor.

"The footprints start here, on this bridge... what was it called again? Do they start from here?"

"It's called 'ma-bridge', Officer Sendou. 'Ma-bridge.'"

"Ah, understood. Ma-bridge."

Muttering the word "ma-bridge", Sendou's feet aligned with his speech as he hastened to step into the crime scene.

"Ah, please wait! Could you put these on?"

Azusa interjected. He held three pairs of rubber boots inscribed with "Iso Police Station", handed over by passing investigators. They likely prevented surplus footprints and blood outside the path.

Donning the boots, they descended a small step onto the actual crime locus. The metal floor resounded with each step taken. The narrowed walkway held about a centimeter of water, and beneath one's feet arose a discomfort akin to treading on damp paper. 

"A sea of blood," Sendou murmured.

"Indeed," Azusa concurred.

"As stated, the water spread here matches the shark tank's makeup. It's a genuine blend of blood and seawater."

"The scattered logs you mentioned are these papers?"

"Yes. It's said to be a record of aquatic life maintenance from the last month. It appeared in this condition immediately post-incident."

Photos surfaced again, showcasing the current location near the entrance, a scene closer to snow. Red, yet only a melting snowy expanse. The trodden papers formed a neat stride extending deeper into the ma-bridge. Aside from that, there was little disarray. However, the papers toward the inner section had already been trampled.

"... Before investigators entered, there was only one trail of steps."
"Sendou compared the photos and glanced back at the entrance they had just passed. The footprints on the paper connected with the red footprints outside the gangway.

"These footprints certainly appear to be from the murderer's escape."

"The journal was brought in by the victim, so it probably scattered when he was killed, right?"

With his neck slashed and his hands going limp, the documents would fall. Hakata imagined the scene and heard Azusa say, "I can't say for sure—this is hard to judge."

"If they scattered by accident, the range would be too wide. Look, there are still papers floating on the water, likely placed to block the drain intentionally."

Azusa explained. The ground of the gangway sloped slightly toward the entrance to direct water to the drain there. The water pooling was also due to the drain being blocked by numerous papers.

"So, I believe the murderer, after killing the victim, scattered the journals he brought by the entrance, blocked the drain, and then splashed water from the tank onto the gangway, creating the current situation."

"But why splash water?"

"Perhaps to obscure the exact location of the murder scene."

"Oh, I see..."

With blood spreading in the water, determining the murder location becomes impossible.

"The murder must have happened in this corridor, right?"

"Yes. Nowhere else had such a substantial amount of blood detected."

The detectives continued to explore this unfamiliar scene above the tank, puzzled but driven. The gangway was slightly more than a meter wide, so they proceeded single file. The railings on either side were about eighty centimeters high, with vertical poles standing like those of a prison cell. Perhaps due to the seawater from the tank, the handrail rust was evident.

Azusa stopped in the middle of the gangway, where the papers were already trampled messily.

"The exact location is unclear, but we suspect the murder scene is here in the middle... because it's close to the point where the body fell into the water."

He gestured to the right side of the corridor. Part of the railing could open outwards like a door, about sixty centimeters wide. Similar to a small door by a restaurant cashier or one of the swing doors in a western saloon.

"After cutting the victim's neck, the murderer pushed him out from here. The photo happens to capture directly below this point."

Blood stained the upper railing, not mixed with water; it had congealed into a reddish-brown, merging with the rust for a mottled pattern. Closer inspection revealed a simple latch between the door and the rail it hinged with, like a bathroom stall.

"This latch, right after the incident..."

"It was open. In fact, the door itself was wide open."

Azusa produced an unseen photo showing the open door, blood on it, and the murky water behind. It gave a sense of loss, as if teetering on the edge with just one lone pair of shoes left.

Hakata reached out and pushed it; with a "squeak," it swung open smoothly. He grabbed the railing with the latch hole with his left hand and leaned out.

On the murky water's surface, several torn pages still floated like the remnants of earlier chaos. Even knowing there were no sharks inside, it was chilling. "What a cruel case..."

At that very moment, when he muttered to himself—

Snap!

A chill pierced through the thin gloves and swept across his gripping left hand on the rail.

"Ah!"

He gasped involuntarily, nearly falling into the tank. At the last second, he clutched the rail again, panting as he pulled back to meet Sendou's cold gaze.

"What are you doing?"

"No, no, it was just water suddenly falling on my hand..."

He immediately looked up at the ceiling. Above the gangway were several pipes, one evidently leaking. He froze, waiting, and soon another drop fell at the same spot.

Azusa laughed, "I said earlier, this is an old building. Though the tank facilities appear advanced."

"They should improve other parts, too. I almost met the victim's fate..."

"Hakata, wait!"

Sendou suddenly stopped his subordinate's actions loudly.

"...What is it?"

"Foot, your foot. No, don't move! Stay right there!"

He squatted beside Hakata, searching through the pulpy paper soaked in water—and picked up a small object.

"A thumbtack."

A perfectly ordinary thumbtack with a smooth head.

"Looks like the investigators missed it... Why would there be a thumbtack here?"

"How should I know! Officer Azusa, please hand it over to the forensic department."

"Oh, okay."

Azusa promptly drew out a plastic evidence bag from his pocket and respectfully received the thumbtack. Sendou continued examining around the opening, but found nothing else. Soon, he made a reluctant conclusion: "The victim was likely attacked on this bridge and pushed from here."

He opened and closed the small door at the opening and asked Azusa, "Hmm, and about the murder weapon, was it indeed found in this passage?"

"Yes, right over there."

Azusa led them further inwards. Hakata hadn't forgotten to whisper to Sendou, "This is called a 'gangway'!" Of course, Sendou poked him again.

About seven or eight meters from the entrance, at the hallway's end by the wall, there weren't any papers because the floor sloped toward the entrance, and there wasn't blood or water. However, ahead was a thick-bladed vegetable knife wrapped in a towel.

Sendou took it in his hand and unfolded the towel. It was immediately apparent that both the towel and knife were bloodstained.

"Indeed, if someone slit their throat and then fell from the opening, they couldn't possibly place the knife so far away."

Hakata compared the knife to the opening.

"After cutting the throat, they couldn't calmly wrap the knife with a towel either... Officer Azusa, you win. This is undoubtedly a murder."

Though no one remembered betting with him, Hakata admitted defeat nonetheless.

"Luckily, you weren't eaten by a shark," Azusa joked before continuing, "We're investigating where this knife came from. It doesn't seem to belong to the facility. We estimate the towel was the victim’s, worn around the waist. Because, although the part below his abdomen remains in the tank, the towel wasn't found."

This method of determination was undeniably horrid. Hakata felt something rising up his throat again. He desperately swallowed it down and continued jotting in his notebook.

"What about fingerprints?"

Sendou asked, without much expectation.

"Neither the knife nor anywhere else had fingerprints collected. This is because there was a pair of rubber gloves thrown into the tank over there—carefully turned inside out. Presumably, they were worn by the murderer."

"Where were the rubber gloves originally placed?"

"They were with the boots on the shelf at the entrance."

"...Hmm."

The gloves were spare items from the shelf, and being inside-out rendered it impossible to lift fingerprints for identifying the perpetrator on them.

Undoubtedly, this was a murder case. The time, location, and method were clear.

But, "who" did it? The crucial aspect of the murderer's true identity remained unsolved.

"That's all we can decipher here... Alright, let's go back."

Apparently, losing hope, Sendou moved towards the opening of the gangway. Hakata closely followed, cautiously saying, "The murderer was remarkably careful."

"I wouldn't say that."

"But the murderer left no trace. They wore gloves and even boots, very cautious..."

"Don’t you find something odd about those rubber boots?"

He swapped his shoes at the exit, then retraced the murderer’s path via the red footprints—from the gangway, across the sink, back to the door.

"The boots were stored in the corner of the rack. However, the footprints themselves...you see...passed the rack and extended to the door. Typically, the rack should be last stop."

"Hmm, perhaps the murderer eagerly fled the scene, reached the door only to realize they were still wearing boots, hence returned?"

"But the perpetrator deliberately altered their stride!"

Sendou fixed his long, elegant eyes on the ground.

"So, the murderer was very mindful of their footprints. Would such a person forget they were still wearing boots?"

"Oh..."

Paying attention to one's steps while forgetting boots worn seems absurd. Hakata recalled Sendou's demeanor when first examining the footprints, realizing what truly concerned him.

"So, the murderer intentionally walked to the door, then returned to deal with the boots."

"At one point reaching the door... why?"

"Naturally, there was something urgent needing attention at the door... like there."

Sendou slowly extended his finger.

In front of his stretched-out finger was an old cabinet storing cleaning supplies.

"Officer Azusa, have you checked the cabinet?"

"The cabinet? We haven't thoroughly checked it outside the gangway yet. Of course, we will immediately... Ah!"

Even before he finished speaking, Sendou already opened the cabinet door. Rust flakes fell.

Inside lay a casually placed bucket. Moving it aside revealed a mop. It was a kind seen everywhere, with a long handle ending in a bunch of twisted cords, yet something unusual stood out.

The cords bore a mark, its color faded but unmistakably blood.

"Seems the perpetrator needed to conceal this thing."

The mop handle was yellow, about a meter long. Hmm—Sendou hummed and picked it up. The mop's screw appeared loose, wobbling where the handle joined. The base of the cord retained conspicuous bloodstains, combined with the same white fibers found on the boot sole. Though, nearing the mop head, the color lightened.

It was as if washed with water.

"The murderer probably washed the mop at the sink."

"It seems so. The stains by the sink are from the mop too."

Sendou was already aware. Indeed, if standing the mop on the floor before washing, it would leave square marks by the sink.

Next, he extracted the bucket—a blue plastic one, its color somewhat darker than the light blue buckets on the shelf. Its diameter and height were around twenty-five centimeters. Along the side, it bore the words "For floor cleaning" in marker. The intriguing part lay in the inside—along the circular base's edge adhered blood and paper fibers.

"Huh?"

Sendou, inspecting the bucket from every angle, suddenly exclaimed. Hakata followed his gaze and noticed light seeping through the bucket’s bottom.

"...The bucket leaks."

"It's got holes? Looks like a crack."

Hakata immediately understood. If filled the bucket with water, carrying it as the murderer did, the water would steadily drip through the crack. Indeed, like the droplets beside the footprints.

"The murderer must have used this bucket to scoop water from the tank."

No need for forensic checks anymore. It was apparent to anyone that this was a critical piece of evidence. Sendou handed the mop and bucket to Azusa, who was probably overzealous in receiving them. He dropped a photo he held in one hand.

"Well done! The mystery of the water droplets and bloodstains solved!"

Hakata crouched to pick up the photos scattered on the ground for Azusa, who had his hands full, just as Sendou exclaimed in excitement, "Isn't it clear now? The murderer isn't the cautious one."

With a hint of a smile, Sendou continued, "The main challenge begins now. If we investigate alibis for the moment of the crime, we can narrow the suspect list significantly."

Yes, the suspects were already identified. Although no fingerprints were collected on-site, several clues were discovered.

We were drawing closer to the truth—Hakata savored this familiar sensation. The caviar and shark fin were almost within reach.

The eager anticipation caused him to tighten his grip on the retrieved photos—then he frowned and said, "Huh?"

"What is it?"

"In some of these crime scene photos, there are people captured in the corners. They aren't forensic officers or detectives, dressed in yellow T-shirts..."

Among the T-shirt-wearing individuals was a fit, short-haired young man, a plump middle-aged woman, and an elderly man idly folding his arms. They appeared to be aquarium staff.

"Officer Azusa, what's the story with these?"

Azusa apologized, bowing his head, "Sorry! I should've reported this earlier. Some of these photos were not taken by us. The ground footprints, the drain situation, and the gangway from outside were shot by a witness."

"Like the first photo taken from outside the shark tank?"

"Yes, exactly. That was the same child who took it."

Child? This term raised a flag. Not an adult?

"Today, a few school newspaper reporters happened to visit from a high school. At the crime moment, they, along with the director, were just in front of the shark tank and promptly came here, earnestly assisting us a lot. For example, preventing others from entering the gangway, instructing to avoid leaving footprints, and taking many photos like these. Thanks to them, the site was well preserved."

"Oh, I see..."

Hakata and Sendou exchanged surreptitious glances, evoking a part of unpleasant June memories related to the high school newspaper club.

Azusa continued with words that turned ominous hunches into reality: "They said they were from Kazekozan High, perhaps you two have met them."

"Kaze, Kazekozan? The newspaper club from Kazekozan? The gymnasium incident?"

"Yes, Kazekozan. The case you two were in charge of."

Azusa proudly noted, though the police department duo had no time for contentment.

"I doubt it, but was there a girl with red-framed glasses?"

"A girl named Sakasaka. Surely it wasn't her? Don't tell me it was her!"

Both pursued relentlessly. Azusa, looking indifferent, said, "Yes, her. The president’s last name is Sakasaka. She's a cute girl. Haha, it seems you know her."

"What on earth is this?"

Sendou covered his face with one hand, looking up at the ceiling filled with pipes. With a "snap," the photos slipped from Hakata’s hand.

* 

"Hakata, you can do it!"

A loud voice called from behind Yuzuno. She turned back to see Captain Sugawa. It seemed Sugawa was preparing for her own nearby table. Alright, okay, Yuzuno forced a nervous smile. She thought, it won't help facing the opponent to appear next... She felt her face stiffening.

The elimination round proceeded smoothly and reached its decisive moment in less than thirty minutes. Yuzuno was naturally unprepared mentally, standing stiffly before the table, facing Choko Shinjiritsu.

She was taller than Yuzuno, carrying an ever-present relaxed smile at her lips.

"Please, take care of me!"

"Yes, please take care of me!"

After shaking hands, they exchanged rackets. However, Shinjiritsu's playing style was nationally renowned; there was no need to closely inspect the rubber. Her racket was a shakehand type, with a large pimple rubber on one side. It was meticulously maintained, so clean that Yuzuno felt ashamed of the dirt on her penhold racket.

Yuzuno lifted her head, her gaze meeting Shinjiritsu's. Shinjiritsu slightly tilted her head, squinted as if appraising the racket and evaluating Yuzuno herself. With her mid-length hair tied for the match, childlike face, snow-white skin, and slender limbs—Yuzuno felt that her often-ridiculed literary girl image had been assessed from head to toe."
She felt her face flush, but it had nothing to do with the tension of the match. They returned each other's rackets and used rock-paper-scissors to decide who would serve and defend. Shinjiritsu won, but she chose to defend, so Yuzuno would serve. The two separated and stood facing each other again from opposite ends of the table.

"Best of three sets, serve from Hakata. Zero-zero."

From the second round, the loser of the previous game served as the umpire, so the scoreboard was manned by the player who had just competed against Yuzuno, Matoba. During the break, Shinjiritsu adjusted the sports watch on her wrist as if she was setting it. Perhaps she intended to time the match.

"Well, is it okay?"

"Oh, sorry. We can start."

"Then, please take it easy on me."

"Take it easy? Sure, no problem."

She readily agreed. Yuzuno was somewhat surprised and then refocused her attention on the match. Her opponent was the strongest female table tennis player in Kanto. Whether she gave her all or her teammates cheered her on, there was no hope of winning.

However, she shouldn't run away from the battle. Captain Sugawa also said, "Hold victory in your heart..."

She swallowed her saliva and tossed the ball high. Then, the sound of the first ball for this match echoed on the table. 

Yuzuno put all her strength into this serve, but Shinjiritsu returned it effortlessly. Yuzuno quickly adjusted her posture and hit the ball again. The rally continued rapidly for two or three exchanges.

Soon, Yuzuno felt a slight unease.

—Was she actually managing to rally with this player?

Shinjiritsu's basic strategy was defense. She persistently used defensive shots, waiting for the opponent's mistake. Against a close-to-the-table offensive player like Yuzuno, a purely defensive approach was understandable. But the ball speed was slow, and the spin wasn't tricky, making it hard to believe that this was the play of the strongest in Kanto.

Maybe she was indeed going easy on her as promised initially? If that was the case, judging by the current offensive, Yuzuno could go on the attack. Though by this thought, she was underestimating her opponent.

A chance presented itself! 

Yuzuno decided to direct the ball to the opponent's right zone—Shinjiritsu was left-handed, so the right would be her backhand, which might be awkward for her. Against another soft return of an unknown count, Yuzuno delivered a heavy backspin. She trusted her control, and the ball landed beautifully where she aimed.

Almost at the same time, a breeze brushed past her face. She neither heard the sound of a hit nor felt the ball's recoil. The ball, close to a horizontal trajectory, spun rapidly over the table. To an outsider, it might seem like no different from a normal return, something Yuzuno couldn't react to at all.

"………"

"One–zero."

Shinjiritsu announced the score in place of Matoba, who was dumbfounded. Her beautiful face still carried a composed smile.

Indeed, she had taken it easy in the early part of the game, and this last shot was hardly serious. Yet, Yuzuno felt no discontent, only bewilderment at the vast gulf between them.

Yuzuno picked up the ball and set her serve stance again. In her mind, as large as herself, Sanae’s voice repeatedly shouted loudly: “It’s over! It’s over!” Even with the determination to win and facing cheers, the pale-faced Yuzuno once again realized—

They were in completely different leagues!

The qualifying rounds continued, and everyone immersed in their own matches and refereeing duties scarcely paid any attention to the match between Choko Shinjiritsu and Yuzuno Hakata. It was a blessing in disguise. Had some paid attention, they’d have witnessed an unfairly harsh, monotonous match. 

As long as Yuzuno was observing, rallies went on. But whenever she tried to attack, Shinjiritsu would counter swiftly and score immediately. That was the repeated pattern, no matter how many times it happened. In the first game, Shinjiritsu only lost one point, and in the second game, none at all. Matoba promptly declared the match over.

"Eleven to zero. Shinjiritsu wins. The match is finished."

In a blink, Yuzuno lost both games, with Shinjiritsu’s victory as the expected outcome.

"A zero-zero match." 

Finishing with no points was something that hadn’t happened since she started junior high. Yuzuno braced herself with hands on her knees from collapsing halfway. Mentally and physically exhausted, she let down her hair, its tips sticking to her sweaty cheeks.

In stark contrast to the perspiring Yuzuno, Shinjiritsu was nonchalantly checking her wristwatch’s time: “Six minutes thirty seconds… that was short.”

Yuzuno overheard Shinjiritsu mumbling with mild discontent about how two games lasted only six and a half minutes, whereas it usually took nearly ten minutes.

Shinjiritsu adjusted her breath and approached, “Thank you!” she expressed gratitude, extending her hand. Yuzuno shook hands and thanked her in return.

“You played well.”

"…Huh?"

Yuzuno couldn't help but question Shinjiritsu’s sudden compliment.

"You returned the shots I gave you perfectly, and your ball placement was very precise. Your fundamentals are strong!"

“Tha-thank you. However, I didn’t manage to score even a single decent point.”

“Haha, of course. After all, your opponent is me.”

Shinjiritsu glanced down at Yuzuno's school uniform and, changing her tone, still cheerfully said, “However, having such straightforward shots isn't good, immediately shows your target. Though you seem to disguise it with speed, I dislike such blatantly honest play styles.”

“Dis-dislike it…?”

“Yes, especially dislike it,” she said, spreading her hands exaggeratedly, “because it’s exactly like Sugawa’s play style.”

She left behind a smile, leaving Yuzuno with the same sense of confusion as during the match’s ambiguous conversations, and turned away.

Yuzuno felt a faint understanding of why Shinjiritsu considered Sugawa a rival, though only faintly.

“I watched your match.”

Returning to the Kazekozan team, Yuzuno was greeted with a smile from Sanae. (What are you looking at!)

“She was too strong…”

“We knew that from the beginning.”

“No, well, even knowing… Dang it.”

Once the excitement from the match faded, the blow from the skill difference immediately hit her. Only a year older, why is she so strong and uniquely styled? She also looked more mature and beautiful. Well, that doesn’t matter at all.

“Anyway, you've worked hard! Want a drink?”

Sanae offered her half-shared sports drink. Yuzuno accepted with gratitude; her own was long finished.

As Yuzuno drank, Sanae lay beside her, looking skyward: “With this, we both stopped at the second round.”

She had also faced Tangan’s vice-captain, magnificently losing in the second round.

“Did anyone else win?”

“Hmm, all the winners are second-year students from Hiten and Tangan. Sugawa is doing well. Also Ribon, Madobe… Oh, among first-years, only Kosuzu is left. She’s facing Sugawa right now.”

In summary, it was nearly a total defeat. Historically, it had always been like this, when the elimination rounds reached the latter half, most remaining players were from Hiten. And each school considered the team competition in the afternoon the main event.

“By the way, the teacher said, with fewer matches now, we can use the side tables. How about we play until it's our turn to referee?”

"Yeah, playing is fine, but let me rest a bit."

"Huh? You’re so heartless."

“Don’t use ‘heartless’ now; I might truly become heartless…”

“Don’t be so down. Didn’t you play well during the match?”

“Well, it’s because Shinjiritsu went eas… huh?”

A girl in a white uniform approached them; it was Matoba, who had umpired her match. Yuzuno wondered why she was coming over. Matoba pointed to the side tables and said: “I heard we can use those tables. Yuzuno, shall we play a bit, maybe doubles?”

Wow, so straightforward to invite someone from another school. Matoba seemed as energetic and proactive as her boyish appearance.

Yuzuno forgot her fatigue, immediately agreeing: “Sure thing!”

“Hey, weren’t you going to rest? Do you not want to play with me?”

“Of course not. Let’s play together, Sanae. Doubles is okay, right?”

“Yeah, I’ll find a partner too.”

She turned back to Tangan and suddenly returned, like she remembered something, said: “By the way, maybe it’s not my place… but I also thought you played well.”

“Huh?”

“Um, how should I put it, I think you didn’t slack off midway…”

Blushing, she lowered her head and hurried back.

Apparently, she had overheard the conversation between Yuzuno and Sanae.

"……"

"See, like I said, people can tell, right?"

Yuzuno had no words. Suddenly, her good friend patted her on the shoulder and said: “Yuzuno, you were pretty cool just now!”

3: Eleven Suspects!

“Long time no see! How’ve you been?”

“Shut up!”

Hearing the greeting from Koari Sakasaka, whom he hadn’t seen in a month, Sendou coldly retorted.

“What are you doing here?”

“What am I doing here? I’m here for an interview, isn’t that right?”

Turning to the tall man beside her, she swung the camera hanging from her neck. The man, clearly resembling a mixed-blood, silently nodded. Beside him was a boy, small like a child, his build looking like an elementary student. The three high school students had been called from the second meeting room, where related personnel waited, to the first meeting room. Their distinct appearances drained the detectives’ energy.

Behind them were two men, one notably chubby with an impressive beard, and the other, a shaved-headed, righteous-looking man, attentively listening to the conversation. These were the director and the staff member responsible for the sharks.

“...Did that guy not come?”

“You mean Tenma? He didn’t. Tenma’s in his room sleeping now.”

“That's good… really good!”

"Oh, by the way, is my sister here?"

"I invited Yuzuno, but she couldn't come. She said she had a match."

The police officers visibly relaxed, wiping sweat from their brows. Behind them, Azusa asked: “So, they’re someone you know?”

“No, they have nothing to do with it, we've never met them before.”

“Huh? But she said ‘long time no see’ just now…”

“Azusa officer, how about their alibi?”

Switching back to work mode, Sendou interrupted Azusa’s questioning in a raised tone. Azusa quickly produced a notebook and said: “Oh, hang on. Here’s how it is, as I mentioned earlier, the director and newspaper kids were together from 9:50 to 10:07, and the footage evidence proves they were in the exhibition area at the incident's moment. Plus, they have a recording, so regarding their alibi, they’re clean.”

“So, it’s impossible they’re the murderer?”

“Naturally. Otherwise, their photos and testimonies wouldn’t be credible.”

There was already little reason to assume any connection between high school newspaper members and the aquarium staff in a murder plot.

Sendou crossed his arms and turned back to Sakasaka, saying: “In that case, I suppose we should thank you for cooperating with the investigation. Thank you!”

“No, no, I just did what needed to be done.”

“And the main worker was Kuramachi-senpai.”

Beside the embarrassed Sakasaka, the child-like boy spoke. Kuramachi might be that guy with the mixed-race features.

“Oh yes, yes. Amazing little Kura—no, Kuramachi-kun. I didn’t do anything.”

“Oh, I see. I thought so too. Really, Kuramachi-kun, thank you!”

“Huh? Wait, ‘I thought so too,’ what does that mean? Mr. Detective, what do you mean by ‘I thought so too’?”

“Then, what about that man?”

Ignoring Sakasaka, Sendou focused on the tactical, poised-looking man.

“That’s Mr. Fukamori. During the incident, he was always in the new building, his alibi is sound.”

“I see… then we’ll have a talk with the two of you.”

“Alright, alright. I first saw Amamiya enter the shark tank…”

“I was referring to those two, not you!”

Despite occasional loud rebukes from Sendou, the inquiry proceeded smoothly, and the case was documented in Hakata’s notebook.

According to the surveillance record, Sakasaka and her team left the backyard at 9:50. Amamiya should have entered the shark tank room just before then. The photo shows Amamiya falling at 10:07. In merely a minute or so, Sakasaka and her team circled to the rear, and all staff at the B building and the backyard gathered there.

“Well, did you notice anyone escaping through the staff passage at that time?”

The director and the newspaper staff nodded together. Hakata noted bitterly, “The culprit sure escaped quickly!”

The sequence of staff concentrating in the work area was remembered vividly by the mixed-race-faced Kuramachi. He indicated that everyone arrived in pairs or more. As they intuitively sensed this was a murder case, they prohibited anyone from accessing the site and footprints and directly led gathered staff to wait at the second meeting room. Their effort was indeed commendable. Reportedly, the director personally coordinated with the police and aquarium staff.

They gathered further details from Fukamori, the keeper responsible for the sharks, about the tank’s condition. His last inspection was around 9:00, at that time everything was normal. Around 10:00—the incident time, no one had entered the second-floor work area. The water pipe had been broken for several days (at which point, Director Nishinozu awkwardly laughed). Other areas were far apart, so in providing water for the tank, it presumably involved hauling it from the lower horse path opening using buckets.

“Has Amamiya ever been near the shark tank before?”

In response to the question, Fukamori replied in a voice matching his appearance: “No, almost never. While keepers frequently act as substitutes, Amamiya’s main job involves dolphin performances and care, and that’s already a heavy workload.”

“Understood, thank you! We can’t dismiss you yet; please return to the meeting room first.”

With a respectful bow, Sendou instructed a search officer to escort them away. Then he turned to the newspaper club members: “You all behave yourselves… Listen carefully, behave correctly without acting on your own!”

Mindful of his repeated cautions, Sakasaka casually responded: “Sure, sure, we won’t rush off on our own!”

“Yet last time you did act on your own!”

However, Sendou’s loud reprimand didn’t reach the newspaper members, as they promptly closed the door upon departure. Sendou's fists trembled slightly, as though seeking an outlet for growing frustration. 

“Damn it! Of all people, why Kazekozan? And involving those tied to him… truly terrible.”

“Um, Inspector Sendou, earlier you mentioned that last time they acted on their own, what was…?”

“It’s nothing! No need to mind it!”

“Yes, understood! Sorry!”

“Inspector Sendou, please calm down a bit.” Hakata softly reprimanded Sendou. Perhaps because of hearing his sister wasn’t coming, the subordinate remained somewhat composed.

“Unlike the gym last time, there won’t be issues like secret rooms now. And he isn’t here today, so there shouldn’t be trouble.”

“Yeah… yes, yes. Sorry, I overreacted.”

Sendou immediately started calm breathing like an old man. 

When he faced Azusa again, the usual glimmer returned in his narrow eyes. That was the investigative look of a detective, cold and calculated, driving the suspect to a dead end.

“Well then, Officer Azusa, let’s turn this first meeting room into a temporary interrogation room. Gather the information. Then bring in the workers present in the backyard during the incident… how many are there?”

“Eleven.” Hakata glanced at his notebook and immediately replied.

“Eleven people. Summon them one by one.”
“I'll check everyone's alibis one by one.”

“Alright, I'll get right on it.” Azusa saluted earnestly and quickly got into action. They were getting closer to the core of the case—Yusaku was increasingly excited. 

Despite an unexpected complication, the investigation was indeed nearing its conclusion. He reopened his notebook. At the very moment Shigeru Amamiya was pushed off the horseback path—10:07 a.m., the culprit was undoubtedly at the scene. As long as they checked all the alibis one by one, the suspicious person would certainly be caught.

There were eleven suspects. A simple mystery. Solving it would be easy.

Soon, the investigators moved to the meeting room. The whiteboard with the diagram was flipped, leaving only the cold tables and chairs, and two detectives. 

“Let's start with the head of animal care.”

“Okay, please call her in.”

Sendou nodded deeply at Azusa, who poked his head in from the doorway. It was as if the previous conversation with Kaori had been erased from his memory—no, it had actually been erased—his trustworthy demeanor was evident.

“Hakata, get ready to take notes.”

“Okay, understood.”

The duo of the prefectural police adopted an unbeatable stance as they awaited the first suspect.

An hour later, Sendou, Yusaku, and Azusa sat silently around the long table in the meeting room. 

Sendou drummed his fingers on the table, Yusaku clicked his pen, and Azusa shifted his eyes awkwardly between the two of them. They were silent, none willing to speak.

Finally, they all spoke—but it was more to themselves.

“What is this?”

“What is going on?”

“What on earth is happening?”

“……”

Another silence ensued.

“Alright, let me organize my thoughts.”

The one to put an end to this fruitless time was Yusaku. He stood up, turned over the whiteboard with the diagram, picked up a blue permanent marker, and began summarizing the interrogation results against his notes.

“The primary premise is that the culprit cannot be outside these eleven people. Is that correct?”

“No problem. The CCTV footage supports this,” said Azusa.

“That's what I thought. First, we have Takako Izumi, the head of animal care. At the time of the incident, 10:07 a.m., she was in the office—”

* 

“Where were you after 9:50? I was in the animal care room,” Izumi asserted in the meeting room, crossing her legs. Fear was not what she felt; she was past that stage and currently fuming, her breathing was erratic. 

“I was organizing business records.”

“You were still there around 10:07?”

“Oh, at the time of the incident, right? I was in the office next door. I couldn't find last month's care log, so I thought it might be mixed in with the files in the office.”

“You found last month's care log… on the horseback path…”

“That’s right, Amamiya secretly took it. I don’t know why he would do that… and it's called the ‘horseback path’.”

“Huh?”

“‘Horseback path,’ not ‘what’ path.”

“Oh, right, right…”

“The log is already in shambles, isn’t it? What can we do? It's very important.”

“Very important?”

“Of course. But luckily we have electronic data, so it’s not a big problem.”

“What was the exact time you got to the office?”

“I arrived just after ten… I don’t remember the precise minute, but it was before 10:05, I think… Oh, right, I ran into Shibaura when I left the animal care room, you can ask him.”

“Okay, we’ll verify that. Was anyone in the office?”

“There were Funami, Jin… and Ayase. I was asking them if they'd seen the log when the director suddenly burst in.”

“You're sure?”

“Absolutely!” Izumi said confidently, her voice loud enough to startle anyone.

*

“At ten-oh-five, Izumi was in the office, with Funami, Jin, Ayase. Funami was working the whole time, Jin took a fifteen-minute break in the archives, and Ayase was in the director’s office for a while…”

*

“Uh, you mentioned 9:50 earlier? Before that, Izumi gave me some documents, a financial summary. I was in the office checking those until then,” the finance clerk Funami answered, stroking his long, unshaven beard. He seemed jittery, the pressure of the case clearly etched on his face, his brows furrowed into a neat arch. The first button of his T-shirt was undone, giving a casual look. The director was the same. Apparently, no one here needed to wear a tie, which was enviable.

Asked about the comings and goings in the office, he responded, “Huh? I don’t really remember. Jin and Mizuhara left… Jin returned shortly after ten. Ah, precise time? Maybe 10:02 or 03?”

This roughly aligned with Izumi’s testimony.

“Then, almost at the same time, Ayase came in and made some coffee. Yes, because only the office has a coffee maker. Then Izumi came in, asking if anyone had seen the log. The log, it was what Amamiya took, right?”

“Yes, that’s correct. It was... discovered at the scene.”

Sendou seemed fed up, trying not to sound humiliated.

“So, at the critical time of 10:07, there were four people in the office?”

“Indeed. The director barged in suddenly, giving us a fright,” Funami shrugged and smiled wryly.

*

“Your surname is really memorable,” Hakata mentioned, to which Jin beamed. Seeing his expression, Hakata regretted it. To Jin, it was probably a cherished topic. The black-haired man chattered endlessly: “Right? Everyone says that. Even back in elementary…” It took some effort to get him seated and start questioning.

“From 9:47 to 10:02, I was alone in the archives. Door closed.”

His precise answer seemed deliberate.

“I was in the archives, not for anything special, just needed a break. After 15 minutes, feeling rested, I returned to the office. Funami was there, closely followed by Ayase, and then Izumi. That was about 10:03. She kept saying she couldn't find the log and reminded us not to slack off. At 10:07, the director came rushing in yelling ‘it’s bad, it’s bad’.”

“You remember so precisely, down to the minute,” Sendou said cautiously.

Jin laughed: “I have exceptional memory and focus,” tapping his head, his demeanor leaving it unclear whether he was somber or cheerful. In any case, his testimony was consistent with the others.

*

“I took the high school student to see the director, and was in the director's office until a little after ten.”

The young deputy director Ayase responded promptly. Despite her saying the title of deputy director was just a name, unlike the previous three, she projected authority with her posture and demeanor.

“I confirmed earlier, like here, there's a small window on the door.”

“That’s right.”

“Did you see anyone passing by in the corridor?”

She avoided the detectives’ eyes and answered after a brief thought, “Well… I wasn’t paying attention, so I only noticed Jin returning from the archives.”

“That’s fine, no problem. And then, you went to the office around 10:02 for coffee?”

“Yes. I saw Jin return, felt thirsty myself, so went to the office.”

“Are you sure it was 10:02?”

“I can’t be completely certain, but I checked the time just past ten, so I think it must have been then.”

Her subsequent testimony was consistent with Izumi and the others. Sendou nodded towards Hakata, who closed his notebook and said, “Thank you very much. You may go now.”

*

“At the critical moment of 10:07, all four of their testimonies align, confirming their presence in the office.”

He wrote Funami, Jin, Ayase below “Izumi.”

“Thus, they have alibis and couldn't have pushed Amamiya.”

“Yes.”

“Agreed.”

Azusa and Sendou both confirmed. Hakata marked a big cross over the names of the office's four people with a blue pen.

—Izumi, Funami, Jin, Ayase, excluded.

“Next, the west side of the second floor.”

He pointed with a pen at two rooms by the stairs, one being the exhibition workshop, the other the women's changing room.

Checking his notebook, he said, “Riki Mizuhara responsible for exhibitions was in the workshop, and Tomoka Takino, responsible for dolphins, was in the changing room. But Takino was planning to return to the animal care room near ten—”

*

Tomoka Takino worked closely with the victim and was deemed as having potentially strong motives by the detectives. Being careful with his words, Sendou slowly asked, “Izumi and the newspaper members' testimony indicates you were in the animal care room until 9:50. Where did you go afterward?”

“I went to the women's changing room… I was looking for a replacement dog whistle.”

Takino answered cautiously.

“Oh, I see. The dog whistle is…”

“Used to train dolphins, to signal feeding and jumping times.”

“Always seen at shows. I see, I see.”

Standing behind the casually chatting Sendou, Yusaku marked the notes for follow-up checks. The dog whistle’s loss might be an excuse.

“I searched in the locker for ten minutes and only found an old one. I thought it would work, and was about to return when Riki outside the workshop called me over.”

“Riki?”

“She’s a clerk responsible for exhibition planning and layout. She asked which poster design I thought was better. So, we chatted in the hallway for a bit, then heard the director shouting…”

“Hold on. When exactly did Riki call you over?”

“Right before ten.”

“And you stayed with Riki? Until 10:07?”

“Yes, together the whole time.”

“… You mentioned being in the hallway. Did you see anyone else?”

“No, no one… oh, I greeted Shibaura on the stairs, saying, ‘you’ve worked hard.’ The exact time, I can’t recall.”

Her increasingly animated tone suggested her regular performance manner. Sendou, after saying “Got it,” wrapped up his questions.

Finally, since she still carried the replacement dog whistle, the detectives asked for a demonstration. The small whistle was already faded, and though made of metal, looked fragile.

*

“Around 9:50, because my work needed the printer, I went to the workshop. Huh? Oh, similar time as Takino… no, slightly earlier. Upon entering, I saw her passing by. Yes, the workshop door is like here, with a window.”

Riki Mizuhara spoke quickly, appearing over thirty but possessing an overall style—fluffy hair, flamboyant glasses, branded T-shirt—that seemed somewhat unsophisticated.

“I printed a few samples and was struggling to choose one. Then I saw Tomoka exiting and called her to discuss… around ten, about 9:57.”

“Sure of that?”

“Positive. I had just checked my watch, thinking it was nearly ten, then saw Tomoka passing.”

Riki showed her watch, band yellow, identical to others’. It seemed to be standard issue at the aquarium.

Having heard both answers, Hakata, as directed by Sendou, went to verify the west side of Building B. The workshop was a simple room with only a printer and shelves, while the changing rooms, both female and male ones, he visited, were cluttered with garments, luggage, towels, making a ten-minute search for lost items understandable.

*

“—At 10:07, the two occupied the corridor outside the exhibition workshop. Thus, both have alibis and couldn’t have committed the crime.”

“It seems so.”

“No problem.”

Hearing the responses, Hakata noted “Takino” and “Mizuhara” at the west corridor’s location, marking them.

—Takino, Mizuhara, excluded.

Moving to the next location, they continued.

“Six people on the second floor. Remaining are on the first floor, starting with zookeepers Tokuro Shibaura and Kai Oiso. These two—”

*

“I was in the feed preparation room.”

The short-haired youth, Kai Oiso, answered calmly. His intense gaze resembled Sendou’s, in some angles, somewhat intimidating.

“Feed preparation room? That’s where fish feed is made?”

“Yes. Today we were slicing jack mackerel for tank feeding in Building A. After arriving at 9:40, we stayed in the preparation room. Shibaura noticed he’d forgotten his notebook and went upstairs, but returned just past ten.”

“Zookeepers make the feed, huh? Past ten, when exactly?”

“Uh… I checked … but forgot the exact time. But definitely before 10:05.”

His testimony matched Izumi’s.

“Then at 10:07—the time of the incident—”

“We were both in the preparation room. We heard the director yelling, unsure of the situation, and hurried to the second floor.”

“Hm…”

While Sendou pondered, Oiso remained expressionless, still.

Apparently, Amamiya’s death didn’t greatly shock him.

*

“Yes, I went to the second floor men’s changing room to get my notebook.”

Though trying to conceal his unstable mood, Tokuro Shibaura failed. His tone was calm, but his wrinkled face showed embarrassment. His bony right hand seemed to suppress nerves, tightly gripping the other wrist.

“I handle freshwater fish, noting observations in a notebook. While preparing feed, I was going to write my name and time on the duty roster, but realized I forgot both the pen and notebook. Kai had a pen, so it wasn’t necessary, yet I thought of getting my notebook.”

“You didn’t go to the animal care room, instead to the changing room?”

“I can’t recall seeing my notebook there, doubted if I’d left it in the changing room… Is this, this a problem?”

The elderly man leaned forward, appearing tearful. Sendou quickly assured him, “No, it’s fine. But according to Oiso, you spent about 20 minutes in the changing room, despite its disarray. A pen and notebook wouldn’t take that long, right?”

“The notebook was in the innermost pocket of my bag, took about ten minutes to find. I did call out in the hallway, someone may remember.”

“Oh, at fifty minutes? Newspaper members and the director confirmed. Still ten minutes remained, were you slacking off?”

“Heh, like Mr. Jin?”

Shibaura’s face brightened. Apparently, Jin slacking off wasn’t rare, not just today.

“Ah, at my age, one tends to feel tired.”
"Although there is a reason for this, I am more concerned about whether Oiso can handle it alone."

"...What do you mean by that?"

"He just started this year and is still an intern. He usually works with other zookeepers. But I think he's almost ready, so..."

"You deliberately stayed in the changing room for a long time. Were you alone?"

"Yes, I was alone... will that be a problem?"

Once again, he leaned in close. This time, it was Sendou's turn to be perplexed.

"No, no, that's not what I meant... We're just interested in the reason. But more importantly, when did you return to the zookeeper's room?"

"Oh, at 10:03. I checked the clock and marked it on the duty roster, so there's no mistake. By the way, when I came out of the changing room, I greeted Izumi and Mizuhara in the hallway."

"Yes, we heard about that. So it was 10:03..."

"I also have faith in Oiso. He's doing a great job."

The senior zookeeper, who was caring and considerate towards his subordinates, finished his statement.

"Therefore, starting from 10:03, these two have been together the whole time."

In the feed preparation room beside the entrance on the first floor, he wrote "Shibaura" and "Oiso" and said, "So these two also have alibis and couldn't have committed the crime."

"Yes... that's right."

"Can't be denied."

Hakamada drew another cross here. The detectives felt a bit uneasy.

—Shibaura, Oiso, excluded. Eight out of eleven people have been ruled out.

"Hmm... Next is the infirmary next to the feed preparation room. Zookeeper Kandabashi Daitabashi and veterinarian Midorikawa Mitsuhiko were here. But it seems Daitabashi was in the zookeeper's room just before forty-five—"

"I didn't kill anyone!"

Daitabashi declared as soon as he entered the room. Before Sendou even started questioning.

"You all think I did it, don't you! I didn't kill anyone, I'm innocent!"

"No one thinks that, just sit down."

Sendou, accustomed to such outbursts, remained calm. Daitabashi grumbled "it's a setup" as he lowered his huge body onto the steel-framed chair. It's said he's responsible for tropical fish, which is hard to imagine given his burly appearance.

"Mr. Daitabashi, you left the zookeeper's room a little after 9:40, right?"

"Yes, I went to feed the fish in the first-floor tank. The tank next to the shark area houses blue-line damselfish."

"It seems you entered the zookeeper's area through the door where Amamiya disappeared?"

"You see, you're suspecting me!"

Daitabashi shouted.

"We're not suspecting you; we just want to understand the reason."

"There's no reason... I always go from the zookeeper's room to B6 like this. It's quicker than going down the corridor stairs."

"B6 is the tank you're responsible for, right? There is indeed a staircase leading to the first floor in the zookeeper's area."

"That's right, so this case has nothing to do with me. I'm innocent!"

"If you keep saying that, it's only natural people will grow suspicious."

That suggestion worked wonders. Daitabashi immediately shut his mouth, his breathing heavy, as if struggling for air. However, his worried expression only grew more fearsome.

"When did you finish feeding?"

"Before ten... Around 9:55, I guess. I can't remember clearly."

"At that time, Amamiya should still have been above the tank. Did you notice anything?"

"You can't see above the tank from the first floor, so it's unclear. I didn't hear any noise either."

Hakamada recorded the testimony while recalling the earlier scene investigation. Indeed, due to the refrigerator-like mechanical sounds echoing, it was hard to hear distant noises.

"So, did anyone come down to the first floor during your feeding?"

"No one came."

"Oh... When you entered from the entrance, you must have passed in front of the shark tank, right? Did you notice anything then? Something unusual perhaps."

"I already said, I didn't pay attention at all. You should ask Mr. Fukamori about the shark tank. He's responsible for the sharks."

"We want to understand the situation just before the incident… not noticing anything, does that mean everything appeared normal?"

After muttering aloud, Sendou interlaced his fingers and placed them on his knees.

"From now on, try to recall carefully. Where were you and what were you doing after ten?"

"After feeding, I went to the infirmary to talk to the veterinarian. The new clownfish have a contagious disease; I wanted to discuss treatment options with him."

"Did you stay there until the incident happened?"

"Yes. It was shocking, suddenly hearing the director shouting... What I said is true. If you think I'm lying, go ask Dr. Midorikawa."

Forgetting his earlier reluctance, he began rambling again. "So that's it."—Sendou abruptly ended the conversation.

Midorikawa Mitsuhiko, with eyes matching his slim chin, left an intelligent impression. As a veterinarian, all-white attire would suit him well, yet he wore a dark blue T-shirt, showcasing a casual style.

"A little before 9:40, I went to the infirmary downstairs and have been there since. I was reviewing old case files."

He testified calmly, showing little interest.

"Were you alone the whole time, not seeing anyone?"

"Basically, yes. When I entered the building, I saw Ayase, and then shortly before ten, Daitabashi came to the room."

"Shortly before ten. Do you remember the exact time?"

Midorikawa adjusted his glasses with a finger and said, "Around 9:57. We hadn't been talking long when I checked my watch and confirmed it was exactly ten."

Like Mizuhara, he indicated the yellow-strapped watch with his finger.

"And until 10:07...?"

"Yes."

The concise response told the whole story.

These two also—

"These two also have alibis. They were conversing in the infirmary from shortly before ten until 10:07. Meaning, they couldn't have pushed Amamiya down."

Hakamada wrote crosses over "Daitabashi" and "Midorikawa" marked in the infirmary. He crossed with such force that it went a bit crooked.

"...Up to this point, there's no problem, right?"

"Yes, since there is testimony..."

"No way around it."

Azusa and Sendou's faces finally started to pale.

—Daitabashi, Midorikawa, excluded.

Hakamada's fingers shook as he turned to the next page.

"Yes, she started cleaning the corridor in the backyard around 9:40. Starting in front of the ladies' changing room on the second floor—"

"I-I started cleaning from in front of the changing room, to the stairs, then down the stairs..."

Honoka Nishikawa, short in stature with remnants of youthful innocence on her face, appeared very afraid before the detectives, causing Sendou to inadvertently soften his approach.

"Were you cleaning the corridor and stairs the whole time?"

"Y-Yes."

"Did anyone pass by you?"

"While wiping the second-floor corridor, Mizuhara and Takino passed by me. I also saw the director and newspaper club people going downstairs... a-and then, while starting to clean the stairs and reaching the first floor, I saw Shibaura from the second floor..."

Hakamada noted her awkward and stiff testimony one by one. It's estimated she finished cleaning the west side corridor and entered the stairwell around 9:55, reaching the first floor a little past ten.

Upon confirmation, she whispered almost inaudibly, "I think that's right."

"Then after passing Shibaura, what happened?"

"...I cleaned along the first-floor corridor, all the way to the door on the exhibition side... but just as I started, I heard commotion from the exhibition side, and the director also shouted back."

"This was because of the incident. Did you encounter anyone during this time?"

"...No, during this time, I didn't encounter anyone..."

Nishikawa bowed her head. Taking that chance for triumph, Sendou exchanged a smile with Hakamada.

At the time of the incident, she was alone. If she had quickly descended the stairs from the second floor to the stairway entrance, she could easily reach the short time window before the body fell and the director rushed into the side door. Bingo.

Sendou intended to press further and leaned closer to Nishikawa.

"Excuse me!"

The door opened, and Azusa squeezed in. He whispered a report into the ears of the county police duo. The timing of this report was precise but unfortunate.

"The officers in the security room just informed me... the camera caught her."

"What?"

"The entire corridor is within the camera's sight, and she is continuously visible in the footage. From 10:03 to 10:07..."

Sendou quickly took action. He temporarily sent Nishikawa back to her room, then immediately went to the new facility's security room to verify the video contents himself.

As reported, the corridor lies between the two doors leading outside and to the exhibition area. By combining footage from these two cameras, it shows the entire area from the stairs to the warehouse, equipment room, and the first-floor west corridor. The footage records the director and newspaper members leaving the exhibition area at fifty, then Shibaura's descent to the feed preparation room at 10:03 was recorded completely. And—

"The camera captured the image of Honoka Nishikawa."

Hakamada wrote "Nishikawa" at the position of the first-floor west corridor.

"At 10:03, she reached the first floor almost simultaneously with Shibaura coming downstairs. As she cleaned the corridor and approached the door to the exhibition area, the director returned. Her movement was entirely recorded in the footage."

Then, like a sigh, he blew on the pen's tip and said, "Which means she has a solid alibi. She couldn't have committed the crime."

He crossed out the last suspect.

Honoka Nishikawa, excluded.

"..."

Neither Sendou nor Azusa spoke. Unable to speak. They just stared motionlessly at the names of suspects marked on the diagram.

The office employees: Funami, Tsutou, Ayase, and Izumi.

The second-floor west corridor: Mizuhara and Takino.

The feed preparation room: Shibaura and Oiso.

The infirmary: Daitabashi and Midorikawa.

And Honoka Nishikawa, who appeared in the corridor camera footage.

Hakamada closed his notebook, summarizing the results of the alibi investigation.

"Based on the above, among the suspects with the conditions to commit the crime... not a single one."

The impossible happened.

Sendou and Hakamada stared intently at the large acrylic tank.

The sign read "Lemon Shark," but now its interior was devoid of any such presence. Only the dark water extended infinitely into the distance. The detectives’ hearts were as cloudy and empty as the tank.

All suspects were with others at the time of the incident or captured on camera, possessing alibis. In other words—

"Could it have been suicide?"

"That's impossible. The position of the weapon, the footprints leaving the scene, and the bloody mop all point to murder."

It was Azusa, not Sendou, who responded to Hakamada.

"Yeah... if so, then someone conspired to falsify testimonies. Meaning there's an accomplice."

"The veterinarian and Daitabashi pair seem the most suspicious as accomplices. These two were not seen by others between 9:50 and 10:07."

"Yes. It's unlikely all four in the office were accomplices, and Honoka, the part-timer, has camera evidence. Among the remaining three pairs, they're most...”

"After seeing the scene, do you sincerely believe this case involved multiple perpetrators?"

Sendou threw this question without turning around.

"Well, well..."

Relying on so-called "detective intuition," Hakamada also felt it was a solo crime, despite having less than three years since his transfer, with underdeveloped intuition. In terms of evidence, the footprints leaving the scene belonged to one person. Also, pushing the victim into the shark tank seems a capricious display of personal emotion, showing the perpetrator's delight in the crime.

"But if it's a single perpetrator, how do you explain the alibi problem? This is almost an impossible murder!"

"...The director and others only witnessed Amamiya falling into the tank; no one saw someone pushing him. Perhaps the culprit had already left the scene by then."

"How can the corpse fall into the tank by itself?"

"What if he was still alive?"

Sendou took a few steps forward, touching the surface of the acrylic.

"After the suspect slit his throat and escaped, Amamiya was still alive. He struggled in the narrow passage and accidentally fell into the tank."

"Reasonable... No, wait," Hakamada wanted to agree but, upon imagining, couldn't help but shake his head, saying, "Not necessarily. Although the passage is narrow, the opening is even narrower. And if the victim was crawling, it's hard to accidentally fall through..."

"Besides, if he had the strength to struggle, he should’ve moved arms and legs upon falling into the water... Oh, sorry."

Azusa seemed to realize only after rebutting and respectfully bowed to Sendou.

"However, Inspector, perhaps your viewpoint that the perpetrator had already fled might be correct. If so, the alibis at 10:07 lose their significance. If that were the case, before returning to the feed preparation room at 10:03, Shibaura, located near the zookeeper's area entrance, becomes suspicious due to his proximity to the men's changing room."

"That's not guaranteed either. All doors along the hallways were closed. Thus, anyone could quietly enter without notice. Even starting from the first floor, one could use the east stairwell to reach the second floor."

"...With no leads," Azusa scratched his curly hair and said, "Well, the issue isn’t about having leads; fundamentally speaking, if the culprit had already left the scene, how they pushed the body from afar remains a mystery."

"From afar... Oh, using a mechanical device for remote operation... Ah!"

Hakamada, speaking out loud, suddenly thought of something. He turned to the detective from Iso Police Station and said, "Detective Azusa, there’s a crane-like mechanism on the ceiling of the zookeeper's area, right?"

"Oh, that's a light crane. It's used for moving fish... Oh, just to explain, it can't be used to push a body."

Before Hakamada could elaborate on his idea, it was dismissed.

"Because it's completely computer-controlled. When the shark was being moved to the truck, I checked the operation history; it wasn't used around the time of the incident."

"No, no..."

Hakamada felt dejected. Even so, Detective Azusa's rebuttal seemed unyielding and too differential.

Isn't there some way? A method to push the body? From the aquarium's backyard, out and into the tank—

"...Got it, it's ice!"

The word 'water' illuminated him. After the brief dejection, Hakamada exclaimed, "The passage was filled with water, right? Could it be to cover up melted ice? Meaning, using ice blocks to hold the body... no, no. Right, if the door was frozen in advance, resting the body on it, then with time passing, it'll fall by itself..."

As he spoke, his voice gradually lowered, his idea sounding silly even to himself.

"In such a hot summer, how can one create ice blocks strong enough to support a body? Even if possible, Amamiya spent a full seventeen minutes in the zookeeper's area. Can so much ice melt entirely in ten minutes?"

"You're right, I'm sorry."

Hakamada bowed his head to Sendou's back.

"At this rate, it indeed seems there are accomplices."

"Or there's another method..."

Despite their friendly cooperation, he and Azusa failed to find answers.

While pondering, a search officer emerged from the nearby working area, gave a slight bow, and said, "It's no good. We've searched the entire zookeeper's area, including all corners of both the first and second floors, but found nothing suspicious."
Aside from the previously withheld items, there was not a single blood reaction found.”

This was a sequence of disappointments, though mostly expected. Despite feeling disheartened, Hakata dutifully noted the results in his notebook. The entire page was filled with reports from the forensic experts.

[Bucket]: A faint luminol reaction was observed on the lower inside part of the bucket, likely from blood mixed with water that remained inside. However, other than this and the actual blood remnants at the bottom of the bucket, no other traces of blood were detected. Concerning the gaps at the bottom of the bucket, tests confirmed that water did seep out gradually when it was filled and carried, leaving droplets identical to those beside the footprints.

Deepmoto, the zookeeper responsible for the sharks, left fingerprints on the bucket handle. However, as he was at the new building during the incident, he couldn’t have committed the crime. Apart from this, traces of gripping with rubber gloves were found on the handle.

[Mop]: Apart from the strands with fresh blood, no other blood was detected. Similar to the bucket, the only fingerprints belonged to Deepmoto, and traces of gripping with rubber gloves were found on the handle.

[Rubber Gloves]: Both glove tips showed luminol reactions, particularly the left-hand fingertips. Since the gloves were thrown into water, no fingerprints were found inside.

[Rubber Boots]: Aside from the blood-stained soles, nothing else was detected. These being communal items, it was nearly impossible to identify the last person to wear them.

[Possessions of Suspects]: All staff wore light clothing, thus only phones, wallets, and notebooks were found in their pockets. Daitabashi held the bucket, and part-timer Nishikawa had the mop. Additionally, the mop wringer Nishikawa used was found in a corner of the west-side staircase, with no detectable traces on these items. Each room was searched thoroughly, but no case-related items were discovered.

[Camera]: Between 9:50 and 10:07, no one aside from the director or someone from the newspaper was seen entering or exiting the backyard. There were no anomalies at the loading dock or outside. No one was seen entering or exiting the equipment room in the west corridor on the first floor, nor did anyone go downstairs to the underground filtration tanks.

[Outside Building B]: A precautionary search was conducted, but nothing was found.

A new report was received.

[Items in the Keeper's Work Area]: Aside from the confiscated items like the mop, nothing suspicious was found in the work areas on the first and second floors.

—In short, “We’ve hit a dead end...”

As for new findings, there was merely the luminol reaction found on both the bucket and gloves, which hinted at traces of blood. Otherwise, it was all “nothing,” “unknown,” and “no findings,” with absolutely no information to pinpoint the culprit.

Hakata snapped his notebook shut with a loud clap, as if trying to dispel his own frustration. Clearly, this should have been a straightforward case, yet any thoughts of caviar or shark fin felt extremely distant now.

“Inspector Sendou, what should we do? Should we question other staff members, or should we head back to the Iso Police Headquarters first...”

“Hakata,” Sendou spoke with his back turned, calmly, “do you remember the first lesson I taught you?”

“...Yes, I remember, 'Put solving the case as the top priority.'”

This was the very first thing Hakata learned after becoming Sendou's subordinate. Finish meals in five minutes. Resist the urge to take baths. Don’t go home. Sleep in the chair. None of these sounded like twenty-first-century advice, but Hakata had prepared his mindset by recording them on the first page of his notebook nonetheless.

“If solving the case is the top priority, then don’t waste time talking here. Even if there’s an accomplice, if it’s a lone culprit, we must uncover what trickery the perpetrator used.”

“Yes, indeed.”

Even if this lone culprit is found, if they provide an alibi, we can't capture them.

“We must quickly find answers, even if it requires aggressive tactics... Speaking of which, since involved personnel have already been drawn in, calling one more person in for questioning probably wouldn’t yield the same results. If it's that person, maybe...”

Looking towards the dark, oppressive water tank, Sendou muttered to himself.

“Involved personnel,” “that person”—his manner of speech gave Hakata an ominous feeling.

“Hey, Inspector Sendou, you wouldn’t...”

“Oh, by the way,” for the first time, Sendou turned to him and said, “I know someone, that guy should be good at solving such problems.”

Sendou seemed to have pinned his hopes on this person, yet his face revealed genuine reluctance. 

*

Shoo! Bang! Wow! 

Simultaneous cheers from Kazekozan echoed with the sound of shoes scraping the floor and fierce smashes. 

Captain Sugawa achieved a complete victory over Hiten’s second-year student.

“Sugawa-san is amazing! She made it to the finals, the finals!”

Bursting with excitement, Yuzuno was the first to run up to the captain, who was wiping her sweat. The knockout round was proceeding smoothly; the first semi-final match had just concluded. With this, the captain's advancement to the finals was assured.

“Thank you! At least this avenges us against Hiten.”

“Weren’t your opponents in the quarterfinals also from Hiten? It's more than just one vendetta avenged! At this rate, the finals too... Ah, but in the finals...”

“Oh dear, congratulations!”

With hands on her hips, Shinjiritsu Choko, dressed in Hiten's team uniform, approached. She was up for the semi-finals next, showing no signs of nervousness.

“You made it to the finals, right? I’m looking forward to our match!”

“...Not sure yet. Shinjiritsu-san, you might lose to Komine-san in the next match.”

“Tangun's captain? No way, I could beat her with my eyes closed!”

Worryingly, her tone didn’t sound like she was joking.

Then Shinjiritsu bent over, looking up at Sugawa, and said: “...Huh? Are you angry?”

“Step aside a moment.”

Sugawa suddenly wrapped her arm around Yuzuno’s shoulder, pulling her close, which made Yuzuno yelp as she felt her cheek bump into Sugawa’s chest; Sugawa’s dignified side profile was right before her eyes.

“Shinjiritsu-san, were you holding back when you played against Hakata? I was watching you two from another table.”

E-everything was caught by her eyes...

“Come on. She asked me to 'go easy' on her, you see.”

“So what? Who would take that seriously? Shinjiritsu-san, though you indeed have more than enough skill to beat her, serving slow and smugly taking your time—I see it as insulting your opponent.”

Shinjiritsu didn’t refute, only shrugged. Sugawa continued:

“While I respect you, I don't like that aspect of you.”

She spoke with directness.

“...I’ll say the same right back at you.”

With those words, Shinjiritsu spun around gracefully and headed towards the table where Tangun’s captain awaited. She wasn’t fazed, even smiling with delight just before she turned around.

Yuzuno, still dazed, felt a surge in pressure from Captain Sugawa’s hand on her shoulder, “Hakata, I’m determined to avenge you, leave it to me!”

“Ah, no need, no need. I don’t really—”

Even if she denied it, Sugawa didn’t listen. Sugawa departed with a stern look. As she passed by, early runner-up up Nonami came to Yuzuno's side, voicing what was in Yuzuno’s heart: “That’s quite the escalation.”

“Well, it doesn’t matter whether it’s revenge... I mean, of course, I want the captain to win.”

Just as she sighed, a thought flashed across her mind—

If Shinjiritsu really underestimated her, would she praise her play post-match? Would she give her pointers?

Back then, just before the match, Sugawa came to cheer for Yuzuno, and Shinjiritsu should have heard it too. Could it be that Shinjiritsu noticed the captain watching and intentionally held back to provoke her?

Shinjiritsu did say that playing against difficult opponents is good training.

Then, provoking the opponent, making your adversary detest you, clashing with the most incompatible opponent in their worst state, would make for—

“...No, that’s impossible.”

“Say what?”

“Oh, nothing, nothing. More importantly, let’s have lunch, lunch.”

Yuzuno pushed the thought far away and headed towards her backpack by the wall. In truth, she was ravenous. It was already past one o'clock.

As food was prohibited inside the gymnasium, she took her bag and went outdoors. During this, she repeatedly heard cheers erupt behind her. It was likely that Shinjiritsu was achieving an overwhelming lead against Tangun’s captain. If possible, she’d like to watch the match too. But what was most crucial was the forthcoming finals. She needed to replenish her energy or she wouldn’t have enough strength to cheer.

Exiting the gymnasium, the heat of the enclosed space eased somewhat, but the sunlight was overly intense. She and Nonami sat in the shade along a corridor and pulled out their convenience store-bought lunches.

“Oh, Yuzuno, a sandwich from 7-Eleven, huh? What filling?”

“Fried chicken cutlet.”

“Fried chicken cutlet? Ah, because it’s for the match, you want some good luck? You really are a romantic, huh.”

“No, it’s not like that.”

“Fried chicken cutlet, for luck!”

“No! Not because of that. Everything else was sold out, so I had no choice but to...”

While the two of them chatted idly, a vibration from her phone sounded inside her bag. The phone displayed a new email message.

Yuzuno, while chewing her fried chicken cutlet sandwich, casually opened her phone to check her inbox. It was from "Yusaku Hakata."

“...What’s up at this time of day?”

No subject. She opened it, and her brother had written in telegraphically terse words—

“A murder case at Marumi Aquarium. Contact Risome Tama immediately.”

Fried chicken cutlet, in Japanese, has a similar pronunciation to “win.”
Chapter Three: The Arrival of the Detective and Clearing the Alibi

1. I Beg My Sister for Help

The incident happened at the end of June in the old gymnasium. The president of the broadcasting club was murdered on a stage that was in a locked room condition. The police suspected Captain Sugawa, who was in the building at the time. In an effort to clear her of suspicion, Yuzuno ran all over the place and eventually found a student. His name was Tama Risome.

Looking back now, what I did then was both reckless and hasty. Despite being the top student in the entire grade, after all, he was just a high schooler. How could he possibly outsmart the police? Besides, when I actually met Risome, he looked so disheveled that he seemed extremely unreliable at first glance. No, not just the first glance—to be honest, it's still hard to believe.

He not only easily cleared the captain of suspicion but also found the culprit and solved the case in just about two days.

"Even so, why are you looking for me?" Yuzuno complained to her brother as her body rushed towards the cultural department building. The finals were about to start, and she really didn't want to leave the competition, but she couldn't get the "Marumi Aquarium" off her mind. Today, Kaori and the newspaper club members were supposed to be there for an interview. Were they caught up in something too?

The last time she came to the Hyakunin Isshu Research Club was two days ago, and it had been quite the scene with a farce about cleaning the room. Yuzuno knocked on the door, but as usual, there was no response. She took out a spare key and opened the door.

"Risome-kun, I have something to talk to you about... wow!"

What suddenly assaulted her was not the air conditioning set at sixteen degrees, but the humidity and heat, even more stifling than the gymnasium she just left. The room was swaying as if everything was in a haze.

"What's going on here? Hey, Risome?"

She entered the room. Not only was it unorganized, it was even messier than two days ago. The once piled-up comics and DVDs had toppled over, completely obscuring the floor.

Risome was lying on the bed where he usually positioned it. No, he was sprawled on the bed.

"Ri… Risome-kun, are you okay…?"

Yuzuno approached him cautiously. Risome was only wearing a T-shirt, exposing his navel, and he had just his underwear on below. The blanket had slid to the side of the bed. His face was covered in sweat, his mouth half-open like a dead man's, occasionally letting out groans of "ugh, ugh." Overall, it was a pathetic sight. He was clearly in a perilous state.

A phone rested by his pillow. At some point, he had switched to a new one, the latest model of a smartphone. Seeing the missed call display, Yuzuno decided to be a little bold. She checked it, and there were five missed calls from "Yusaku Hakata." Her brother had tried contacting her because calling Risome directly yielded no results.

"Water, water… water, water…"

Amidst his groans, Risome managed to utter the word "water." He likely wanted something to drink.

Yuzuno opened the refrigerator. There were only beans and jam inside. She had no choice but to take out a half-drunk sports drink of hers. Risome grabbed the drink with trembling hands and, while lying in bed, skillfully drank it down. This precious hydration for Yuzuno was gulped down by him in an instant.

"I… I thought I was going to die…"

As soon as he removed the plastic bottle from his mouth, his energy began to return, and vitality returned to his face.

"Risome-kun, what happened to you? Why is it so hot in this room?"

"It's all your fault, Hakamada girl..." Risome glared at her angrily. "Because you threw away the remote control…"

"Huh? You haven't found it yet?"

"No, I found it. I dug through the comics to find it."

If possible, please don't just dig through the comics, but tidy them up.

"However, the remote control is broken. The buttons don't work…"

"What?"

"It broke after being tossed around just once? Are you a cyborg Hakeda? What color are you? Black? Silver? Thanks to you, this room has turned into a scorching inferno… two days in the flames, damn it..."

Although she didn't quite understand, it seemed Yuzuno had broken the air conditioner remote.

"But why do you keep the doors and windows shut? If you open a window..."

"Idiot, leaving the windows open for a long time will expose me, right?"

"Oh…"

Now it was clear there was a reason for running the air conditioning. Yuzuno finally understood this point.

"I… I didn't realize. I'm really sorry. But… Risome-kun, it's strange for you to be living here in the first place... Why are you staying here?"

"Stop talking about it. Just leave me alone. I don't want to waste unnecessary energy..."

Risome shifted his position, turning towards another direction.

"Uh, it's cooler outside than in here. You could go to the library across from the station. The air conditioning is great there."

"Not going."

"Why?"

"Trouble."

"..."

Yuzuno's sympathy vanished in an instant. It seemed he was not in a life-or-death situation after all.

"You’re no different from usual. Oh, right."

Yuzuno remembered her original purpose for coming here. She shared the situation with Risome, who had clearly been unaware of the calls from her brother.

"So that's the deal. Let's head to the aquarium right away."

"...Not going."

"Why… is it also because you find it troublesome?"

"In my current state, do I look like I'm willing to move?"

"Ugh, ugh" — he moaned again. Yuzuno remembered two days ago when he had angrily told her not to leak information out of laziness. She wanted to retort, "Don't refuse the police's request just because it's troublesome."

"Kaori might be involved in the case."

"Probably related. They contacted me so quickly, likely because of this."

"Then you should definitely go!"

"But the police wouldn't ask a possibly suspicious related person to help. I might intentionally deduce in a direction favorable to Kaori. If she were killed or injured, they would've written it in the message when they contacted you. But there was nothing like that mentioned. So, it’s probably just like you last time when you witnessed the victim. That’s how I feel."

Though he still lay there facing the wall, his voice still lacked energy, his deduction was persuasive.

"So there's no need to worry."

"But…"

Yuzuno's retort was silenced by the vibration ringing once more. The display showed "Yusaku Hakata," but this time it was a call, not a message.

"Hello?"

"Hello? Yuzuno, did you see the message?"

"Yes, I did. Risome-kun is right in front of me."

"Ah, great! Let him take the call."

It seemed her brother believed that once they got in touch with Risome, he would definitely go, even though this person wasn't easily convinced. Yuzuno internally complained and shoved the phone into the hands of the lazy bum in front of her. He reluctantly took the call and said, "Hi, brother? Hello, this is Risome. Yes... Hm, am I sick? Well, I just went through two days of fiery trials, possibly affected by spores."

His voice sounded as if he were at death's door, possibly because her brother was inquiring about his health condition.

"Yes. Yes… I heard. Kaori? Oh, she's there. She's a witness, right? No, I'm aware of that. Huh? Yes. Yes… Ah, I'd really love to go, but humanity has entered a long period of decline... Huh? I'm saying humans are in decline because I'm a human. I'm equivalent to mankind. Anyway, I won't go this time... Yes, I'm sorry, I can't go. Humans have weakened. Huh? Maybe, but it also depends on my mood. Yes, yes..."

Risome rambled on, using someone else's phone, talked for so long, and still ended up with "I'm really sorry" as he returned the phone to Yuzuno.

"Hey, hey, wait a minute, Risome-kun! Risome! Answer!"

Her brother's voice was incredibly flustered.

"It's me."

"Yuzuno, what's going on? Why won't he go? I said I'd pay him!"

"I dunno, maybe because it's hot and troublesome."

"Troublesome? What kind of joke is that!"

"Hm, I totally get your feelings!"

Yuzuno repeatedly expressed her understanding with sympathy.

"Listen, we're in a pinch here too. Can you take responsibility and bring him over? I’m begging you!"

"Huh? Why does it have to be me? I'm in the middle of a club activity…"

"You're the only one available there now. I'm begging you! No, pleading with you! I’m begging!"

"Ah—"

Yuzuno groaned, just like Risome did earlier. She had thought she was just a messenger, but now found herself embroiled in unexpected trouble. She briefly moved the phone away from her ear and started trying to persuade Risome, "Risome-kun, please agree. You see, weren't you just worrying about the travel expenses to escape a few days ago?"

"What do you mean escaping, it's a summer doujin market. Do you think I'm the culprit...? I'm not short on money. Even if I had more income, I couldn't buy the Staff Book."

"What…"

What should she do now? No matter how much she wanted to fulfill her brother's request, getting this useless person to act required a different approach. The June incident had already taken a lot of effort in this regard. But in the end, agreeing to cover his living expenses (rather, his hobby expenses) was enough, a very simple condition. Yet this time he claimed he wasn't lacking money...

Glancing around the room, her mind racing to think of any suitable bargain she could make——it only took her five seconds to discover one.

"This room's air conditioner, what do you plan to do about it?"

"Isn't the remote broken? The air conditioner itself is also old. However, if you just casually call someone to fix it, the school will find out. Yes, someone needs to discreetly handle this..."

Risome's perpetually lazy body suddenly showed a brief animation of rigidity.

Like a broken clockwork doll, he slowly resumed his supine posture, stretching his arm toward her, and Yuzuno handed the still-active phone to him.

"Hello, brother? ...Alright, I'll go."

He promised while looking up at the air conditioner whose exterior had yellowed.

"Too easy..."

Yuzuno sighed in surprise beside him. Well, in this case, it actually helped her a lot.

"But I have three conditions. First, please give me 100,000 yen as payment. Huh? Yes, the price went up. Like the special discount for the inaugural issue of a magazine... Yes, of course, you can wait for the results before paying. Also, my room's air conditioner was broken by Hakeda, and I want the latest model. Please have someone install it without the school finding out. The fee is naturally on you... Oh, yes, yes, I’ll produce results. Right? Thank you."

Lying on the bed, Risome dominantly negotiated with the other person and continued, "And it's too much trouble to go to you guys, so please send a car to pick me up. Not a car marked as a police vehicle... Right, right. Please send one with good air conditioning."

2. Deduction at Ninety Kilometers Per Hour

Thirty minutes later, the two of them were seated in the back of an unmarked police car, cruising along on the capital expressway. Risome sat cross-legged, relaxed, while Yuzuno held her head.

"How, how did it come to this..."

Getting him to agree was a good thing, but getting Risome outside was a significant struggle.

At first, he didn't want to get out of bed, lying there motionless. When Yuzuno persuaded him to at least put on some clothes, he replied, "You pick out two items for me from over there." After arbitrarily finding him a shirt and pants, he said, "You put them on me!" With some effort, she pushed him off the bed, sometimes kicking his back and other times grabbing his shirt collar, and finally managed to get him into the sunlight. By then, the prefectural police car was already waiting at the north gate.

Handing him off there, like consigning oversized trash to a collection service, would have been the perfect goodbye. Yet Risome kept groaning "ugh, ugh", seeming like he'd collapse at any moment once she let go. Moreover, even if he were driven to the aquarium, there was no guarantee he'd work hard.

Sugawa captain's final would have lots of cheerleaders even without her. Currently, Risome was alone. Besides, when all's said and done, part of the reason he's weakened was due to tossing the remote herself—

Thoughts like these flashed through her mind, and caught between an odd sense of responsibility, maternal instincts, or simply a protective feeling, Yuzuno found herself, upon regaining awareness, also stepping into the car.

And then, no more than a minute after the car started, Yuzuno felt immense regret.

"......"

She glanced resentfully at Risome. He was wearing a cool-toned checkered shirt and three-quarter cargo pants, sandals on his feet, looking quite breezy (Yuzuno matched his attire appropriately). Holding a cola in one hand and a phone in the other, the earlier image was long gone.

It turned out Risome couldn’t stand only the heat, and once cooled by the car’s air conditioning, he was spirited again. Stretching with big yawns, twisting his neck with audible clicks, he constantly remarked, "Ah, that's it, revived, revived!" Partway through, he even had the driver stop at a convenience store.

"You ate pork cutlet and the like?" he suddenly queried.

"Yeah, I had a chicken cutlet sandwich for lunch. Is there a smell?"

"No, your mouth seems to have breadcrumb on it... Oh, is it that? Because there’s a competition, you’re going for some good luck? Winning the match, huh."

"No, it's not that."

"Even though they sound the same, you're going for the auspicious meaning, right?"

"Hmph, you're all like that…"

Yuzuno leaned forward, using the rearview mirror to wipe off the breadcrumb from the corner of her mouth. She exchanged a glance with the driver in the rearview mirror. A young man, looking like someone from a suit store ad, he was an officer from the prefectural police investigation division named Hatori. Earlier, her brother had said, "Finally, a junior younger than me has arrived," probably referring to him.

Hatori always appeared quite anxious, and even his glances at her seemed to be filled with distrust. And understandably so. Tasked with picking up two high school students of uncertain backgrounds, one dressed in table tennis attire, and the other demanding, "I want a drink, so stop by a convenience store." Before driving, he had reluctantly grumbled, "Why am I doing this?"

(Officer Hatori, I guess I know what you're thinking. But I'm also wondering the same—why has the situation turned out like this?)

"Speaking of matches, is leaving in the middle alright?"

The laid-back culprit of the "Why" situation inquired.

"Of course, it's not good to leave! But I don't have a match this afternoon, and I’ve already contacted Sanae."

"Hey, you didn’t really need to come, you're such a do-gooder."

"T-this is all your fault..."

Just as Yuzuno considered punching that picturesque side profile into oblivion, her phone vibrated once more.

Speak of the devil, it was Sanae.

"Hello, Sanae? Sorry, it looks like I can't return. Yes, could you let Captain Sugawa know for me... Ah, right, what's the match status? She’s playing Natsukiri-san in the finals? Hmm… Hmm, how is it? Huh? ...Ah~, figures, she still lost, huh."

Yuzuno felt a bit disappointed; the captain still couldn't best Kanto’s top.

However, the follow-up report lifted her spirits out of dismay.

"Huh? She won a set? Only three points shy in the final set? That's amazing! As expected of Captain Sugawa!"

The intense, neck-and-neck match—just a bit more and they could’ve won. Even with the bit of distance over the phone, Yuzuno jumped up in joy.

"Really? Hmm... Yeah. Okay, I'll definitely go if I can make it to the celebration. Do your best cheering for this afternoon's matches! Yes... Uh? About this? This side is still unclear."

"This side's fine," Risome, seeming to listen in, interjected.

"...Did you hear that? Exactly. Hmm, alright then for now… Huh? ...What? No, there's nothing like that. What are you talking about?"

As Sanae started teasing, Yuzuno hung up, cheeks flushed. Looking over at Risome, she found him indifferent, easing her mind somewhat.

For the next moment, the sound of racing at ninety kilometers per hour dominated the cabin.

I should’ve gone back to the gymnasium—just as Yuzuno absently pondered this, Risome spoke: "You mentioned 'Natsukiri' earlier."
"…Yes."
"The table tennis player Ninjitsu, is that Choko Shinjiritsu?"
"That's her."
"She came to Kazekozan, huh?"
"...Huh? Risome, you know Shinjiritsu?"
She thought he was a man with no connection to sports. Risome's gaze remained on the touch screen as he said, "I know her, but our relationship isn't good; I'd say she's an enemy. She's my third least favorite person in the world."
"Enemy?"
Both Captain Sugawa and Risome used unsettling words when referring to Shinjiritsu.
"What kind of relationship do you have?"
"When we were in junior high, there was… No, you shouldn’t know about this. Forget I said anything, Hakata-girl."
His stiff tone was rather unpleasant.
"Hey, I've been meaning to tell you, can you stop calling me Hakata-girl?"
Being called just Hakata would be one thing, but being called Hakata-girl was uncomfortable when a non-relative used familial terms.
"Why? If I just say Hakata, you might get mixed up with your brother. So I call you Hakata-girl. Do you have another name you prefer?"
"No, I mean…"
"Hakata-sis? Hakata-little one?"
"Forget it."
Yuzuno gave up. She couldn't bring herself to ask him to call her by her name. It would have been acceptable if he suddenly switched to calling her Yuzuno, though it felt a bit awkward too.

As she lamented her helpless mindset, an ill-timed ringtone chimed. It wasn't Yuzuno's phone as she had it on silent, so it must be someone else's. Risome quickly operated the touchscreen and answered the call, "Hello? Oh, it's you, brother. Haven’t heard from you in thirty minutes. Thanks for picking me up. Yes, I'm on my way now."

It seemed to be a call from her brother.
"Yes. Right... Hmm, yeah, if you could tell me now, it'd be great. My time is valuable too. Huh? No, don't look at me like that, I have a lot going on... Right, right. In any case, please quickly explain the situation to me. Saying it's a murder is too vague; it's not like a book title. Please explain what happened in detail…"

Her brother was probably trying to explain the case's situation before they arrived. Yuzuno also hoped to understand it.

Risome, looking bothered, pressed the speakerphone button. Her brother's voice came through, "The incident happened today at 10:07. When Sakasaka and the director were watching the lemon sharks…"

"...Ugh."
Yuzuno immediately regretted it. Was a blood-soaked staff member falling into a tank and getting eaten by sharks? Just hearing it was nauseating. That wretched chicken sandwich seemed to be on the verge of coming up.

Her brother couldn't possibly know how nauseated his sister felt and continued speaking.
The scene was the catwalk above the tank, papers scattered atop the blood. He also mentioned footprints on the papers and outside the catwalk, and they decided to confiscate some evidence like a mop. And on and on.

By the time the car exited the highway and onto Yokosuka Street, the nausea had been replaced by a massive question mark. It was clearly a murder, and the range of suspects was narrowed, but at the exact moment of the crime, everyone had alibis. It seemed straightforward yet incomprehensible, no wonder her brother and others were puzzled.

"That's the situation. Now let me share my thoughts for your consideration…"
"No need. By the way, are there any photos from the scene?"
"Photos? There are many, including some taken by Sakasaka."
"Kaori took them… I see. Then could you send the photos to my email?"

Faced with such an unconventional request, her brother understandably reacted poorly.
"No way, that's confidential investigation material... I can't send it to a personal email."
"Why are you talking about regulations at this point… Alright. Then explain the contents of the photos verbally in detail."
"Huh? You want me to describe them?"
"Have someone else do it then. Oh, since Kaori took them, it might be best to let her explain. Can you hand the phone to Kaori?"

"...Alright, I'll send them. Please wait a moment."
"Why do you always resist? I'm waiting."

As soon as Kaori's name was mentioned, her brother surrendered easily. It was clear that the trouble caused by the newspaper club had already worn him out.

After hanging up, about a minute passed before the phone rang again.
A string of musical notes.
"…I've heard this before, what tune is it?"
"Hunter in the Forest."
After a brief answer, Risome answered the call again. Her brother said, "I've sent them to you."
"Got them, thank you!"

With the speakerphone setting, Risome could check the images without ending the call. As Risome opened each file, she leaned closer to the screen, and Yuzuno likewise peeked in tension.

All the data had been sent over, the first few dozens were ordinary snapshots of the backyard. Following the staff and the fish in the tank, suddenly there was a body, lying in front of the sharks. From that point, scenes of the crime began appearing. One after another, depicting narrow pathways, each photo showing redness.

Risome's fingers halted at a picture of the small gate on the catwalk opening. It was a rusty, unlocked padlock with bloodstained railings around it. He reviewed a few images again, then said, "Hmm… Hey brother, is there an old water pipe above the small gate at the opening?"
"Water pipe? Yes, several. Why are you asking?"
"Okay. Then what about the victim's height and weight?"
"Height? Wait a moment."
The sound of a notebook being flipped was faintly heard.
"One hundred eighty centimeters, sixty-eight kilograms. Slim."
"Sixty-eight kilograms, I see, I see…"
Risome pondered for a moment. On the other side of the street was an old directional sign saying "Yokohama Marumi Aquarium · 500m ahead". Under the sunlight, a thoroughly faded octopus was waving—a tentacle, not a hand—towards the driving lane.

"I think I understand."
He said as they passed the sign, seemingly effortlessly.
"Huh?" "Huh?" "Huh?"
Three different voices echoed in the car: Yuzuno's, her brother's over the phone, and Hatori from the driver's seat.

"You understand? No way…"
"Of course, I understand the problem with the alibis. Brother, you seem to suspect issues like whether there was an accomplice or if it was a suicide, but rest assured, this was a solo operation and clearly a murder. It was a thorough and planned murder."

Despite not yet arriving at the crime scene, even before seeing the aquarium, Risome had already reached a conclusion when they were still 500 meters away.

Glancing at the rearview mirror, Yuzuno saw Hatori had thrown away any concept of safe driving, staring in disbelief as if saying, "How is this possible?"

3. Hello everyone, I am Tama Risome.

It's been eight years since the last time I came here, back in elementary school. Marumi Aquarium, full of nostalgia.
The octopus on the sign smiles invitingly, just as I remember. But unlike those memories, there's now no sight of visitors around here, and two men already waiting at the front entrance—a new experience from my memories.

Among the two men, one was a young man with neatly organized bangs, looking like someone new to the workforce. The other had elongated eyebrows, white hair, and his tall stature exuded an intimidating presence.

That was Yuzuno's brother, Yusaku Hakata, and his boss, Inspector Sendou.

"Yuzu, Yuzu, Yuzuno, how come you're here too?"
Seeing her, her brother was flustered.
"What, didn't you say it yourself, brother? Told me to be responsible and bring him along."
"Huh? Oh… I did say that, but that's not what I meant…"

Yuzuno swallowed the words lingering in her throat, "I didn't want to come either." Anything more would complicate the issue.

Beside them, two fates confronted each other once again.
"Oh my, haven't seen you in a month, Detective. Did you miss me? Even called me up."
"I'd prefer not to see you if possible, didn't even want to call you here. I'd rather never see you again my whole life."
"But you did call me here, didn't you? Geez, what a tsundere. You're too cute, Detective."
"Enough babbling," Sendou frowned, "I hear you've solved the mystery of the alibis, is it true?"
"Of course."
"…You figured it all out in the car?"
"Having an explanation and photos were enough. But there are a few things I want to confirm; can you take me to the scene?"

Despite it being a month since they've last met, Risome remained assertive with the police. Whether premeditatedly to avoid being underestimated or simply finding amusement in teasing the police, it was hard to tell. Sendou waved them over, leading the two into the aquarium.

"Let me make it clear, Risome, your job is to clarify the alibis, don’t do anything unnecessary!"
"I wish that too. Getting dragged here involuntarily, just let me head back soon."

Inside the entrance hall after passing through the main door, there was another suit-wearing man waiting there. A man with tousled hair and a dark complexion, probably a local detective.

"Oh, this is the Kenpo's informal advisor… Oh…"
Whatever explanation he was given about Risome, or what kind of image was painted, his bright eyes reminiscent of a young boy's kept looking this way. I wanted to say, "I’m just a tag-along," but the words never came out from Yuzuno.

One fish tank after another appeared, with fish swimming energetically inside. Though coming to the long-desired aquarium just a few days ago, her brother's severe and scary expression and his hurried pace left Yuzuno with no time to enjoy the sights.

The problematic backyard was accessed from the octopus tank's front. Sendou unlocked it, taking them up the corridor's back stairs, pushing open the double doors into a vast space.

The scene before them was as they had seen in the photos earlier. Evidence markers were placed on the shelves in front and on the storage cabinets beside them, and tape marks were drawn on the floor, winding like tracks in a train game. They seemed to be footprints. However, Risome ignored these and headed straight to the large water tank at the back of the room.

This tank extended from the first floor all the way to the ceiling, this must be its upper portion. The waterline was slightly lower than the floor, with a catwalk right at the center for work. From the entrance to the center point, a horrific red carpet was laid, soaked with blood.

The recurring dread made Yuzuno slow down her footsteps. At that moment, her brother grasped her shoulder and said, "You stay here."
"…No, I want to go, I want to understand the situation."
"Don’t go, it’s not something pleasant. Besides, you’re technically a bystander."
"I'm not a bystander; I'm supposed to be his guardian. It's so much trouble getting Risome dressed."

"Huh?"

She pushed aside her brother, who stood rigid, and followed Sendou and the others into the catwalk. They formed a line and advanced through the mess of paper scraps, while Risome had already started his explanation.

"I'll begin with the conclusion. The perpetrator likely devised a timing mechanism, meant to make the victim fall into the tank a while after being killed, thereby creating a perfect alibi for 10:07."

"A timing mechanism? Hakata mentioned something like that… Was it with ice?"
"Ice? Haha, ice wouldn't work. However, the idea is very, very close. The perpetrator’s scheme was indeed a bit foolish."

Having arrived at the opening, Risome first looked up at the ceiling and, understanding, said, "Ah, it’s just as I thought." Then he bent down, repeatedly opened and closed the small gate, nodding along, and finally crouched to scrutinize the connections of the railings, saying, "Got it." Thus concluded his confirmation work.

"Look, Detective, it's right here."
He pointed just below the lock, on the outer side of the railing. Sendou leaned closer, pinching a small wet piece the size of a fingernail. “Isn't this just paper? It's a soaked part of the documents.”
"Indeed, it's soaked paper. But if you analyze its composition, you'll find something interesting."
"…It's not a document?"
"If it were a document, that would be strange. The fact that it's stuck on the outer side of the railing is suspicious. Plus, the outer rail is untreated, yet this is soaked."
"Then what exactly is it?"
Risome placed his hand on the railing he had observed earlier and revealed the answer, "I suspect—it’s toilet paper." 
"Toi, toi, toi… toilet paper?"
The voices of Sendou, the curly-haired detective, and Yuzuno overlapped.
"Yes, toilet paper. All the facts inside the catwalk indicate that it's the case. The scattered documents, the floor soaked in water, the thumbtacks on the ground, the shape of the railing. And the water pipe leaking."
Just as Risome looked up at the ceiling, a droplet fell precisely onto the lock’s latch hole. The old water pipes were leaking. The severe rusting was likely due to this.

"You mean, they tampered with the lock or something?"
Hearing Sendou ask this, Risome shook his head and said, “No, there’s no tampering with the lock. The manipulation is around the railing.”
He grabbed the outermost vertical bar of the small gate at the opening and held it together with the railing connecting vertical bar, closing the door completely.
“This small door has a latch mechanism created with the railing. Therefore, even without locking, without tack pins, you can secure the small door by connecting the two railing bars with something.”
“Ah, you mean with the toilet paper.”
“Exactly. After killing the victim, the perpetrator wrapped a lot of toilet paper around the two vertical bars repeatedly and secured it with thumbtacks. In other words, they could keep the small door in a fixed position even without locking it. Then, the victim was placed leaning on the secured door. And like this, the timing mechanism was set. Afterward, the perpetrator could leisurely escape.”
"Like this? But how can they set the timing?"
"Oh, I see!"
A voice came from behind Yuzuno. When did her brother get here?
"It’s the water leaking from the pipe! The droplets dissolve the paper!"
“Yes, toilet paper easily dissolves in water. And the leak is precisely over the lock—at the connection spot of the gate and the railing. The water droplets gradually dissolve the toilet paper. Eventually, the paper softens and can no longer support the victim's weight. Then what happens?"
Risome released his hold on the railing and pushed the door outward.
"This door opens outward, so naturally, the victim's body would fall directly into the shark tank out there. From the exhibition area view, it appears as though they were pushed."
"If, if that's the case, it indeed allows a delayed fall into the water for the victim!"
The curly-haired detective was so excited saliva was spat everywhere.
"So what happens to the toilet paper then? The partially dissolved paper will break apart here, and with the force of the door opening, it gets flung out. Then it, too, falls into the tank just like the victim. At this time, the shark is near the water’s surface, actively moving, and in its excitement, it aids in..."
The debris of the toilet paper falling into the water would instantly dissolve, disappearing in the waves stirred by the shark—

"Naturally, parts of the toilet paper might remain not fully dissolved or fail to fly outside properly, landing inside the catwalk. Those documents were prepared for them."
Risome stepped firmly on the water-soaked paper on the floor with the sole of his sandal as if extinguishing a cigarette ember. The water-drenched paper immediately changed shape.

"With these things, as long as the specific composition isn't scrutinized, the toilet paper would be disposed of as 'part of scattered documents.' Look, several torn sheets are still floating on the water's surface. The perpetrator intentionally arranged it, so the papers in the water that hadn’t dissolved yet didn’t catch attention."

With this explanation—Risome concluded his short explanation. Then as a parting shot, he added, "This situation proves that even if no one present at the scene, the victim could still fall into the tank."
Therefore, the suspect's alibi for 10:07 is meaningless... However, as toilet paper can't buy much time, the murderer was actually on-site, at most ten minutes away, around 9:57."

Yuzuno pondered over this deduction in her mind, looked around the walkway, and said, "I see..."

The paper and water on the ground, the outward-opening entrance, the leaking drip from the pipe, the scattered paper on the water, and the water and the shark in the tank. Everything was a tool for destroying evidence. The murderer set up several mechanisms repeatedly to destroy the timed device.

It seemed like the detectives present were far more shocked than she was. Her brother darted out from beside Yuzuno, exchanging confused looks with Detective Sendou and others.

"Well, I think there's indeed such a possibility... but as for using toilet paper..."

"No, Detective Sendou, it's definitely like that. The water pipe was leaking, the water pipe was leaking. Didn't I almost slip because of the dripping just now? Ugh, how did I not notice anything then?"

"Oh my, you're truly a great assistant to Detective Sendou. Solving it so easily... I'm so touched!"

Yuzuno accidentally overheard an embarrassing exchange. Her brother, he almost slipped off the walkway. And he was called an "assistant"!

After a brief discussion, it was decided to first examine the paper clinging to the outside of the railing. The curly-haired detective (Sendou called him Azusa) placed a small wad of paper into a plastic bag and quickly left the animal keepers' working area.

After watching him leave, Sendou said to Risome, who was leaning against the railing, "If it turns out this paper is different from the documents beside it... then I'll acknowledge your contribution."

"Thank you. When that happens, please send 100,000 yen and solve the air conditioning problem as well."

"Okay, promises made will be fulfilled. But I didn't expect the fake device to be so simple. A momentary flash of inspiration was all it took—no need to involve you."

"A momentary flash of inspiration?" Risome raised an eyebrow and said, "Unbelievable, Detective. This wasn't a momentary flash. This was a step-by-step, proper deduction."

"How hard could it be? Paper and water pipe leakage, oh, and thumbtacks. Next, just a bit of imagination..."

"That's wrong! It all starts with the condition of the door."

He once again pulled the door he had opened earlier closer. Yuzuno realized that, come to think of it, when Risome was browsing the crime scene photos, the first thing he focused on was the image at the entrance. The scattered paper on the ground wasn't captured at all, which was the basis of Sendou's "imagination."

"This door, here it's stained with fresh blood. You see, it also flowed onto the vertical rail on the railing. If the murderer directly pushed the victim from here, this point would be very strange."

"...Strange how?"

"Hakata girl, have you thrown away furniture recently at home?" 

Risome suddenly threw a question at Yuzuno. Bewildered, Yuzuno replied, "We changed our sofa in February and threw the old one away." She confirmed with her brother who lived under the same roof, and he said, "Huh? February? Has it been that long already?"

"Yeah, I was still in middle school back then."

"Is that so? No wonder the new sofa broke so quickly..."

"The purchase time doesn't matter." Risome interrupted the siblings' conversation. It was all the brother's fault for being so lackadaisical.

"So, you got rid of a sofa. How did you move it out of the house?"

"How? Brother and Dad moved it out from the entryway."

"The front door opens outward, right? Did you push it open?"

"Push it open? Yeah, we opened the door like usual and moved it out."

"You see, Detective, this is what I'm talking about," he said to Sendou standing beside him. "When moving things through a narrow passage, the door is usually opened beforehand. If the murderer opened the door in advance when pushing the victim, there wouldn't be any bloodstains on the door."

"Ah..." The chief detective sighed lightly.

"However, there was a large amount of blood on the door. Why? There could be many reasons, but the most natural one is prolonged contact between the body and the door. In this case, with the railing about 80 cm high, the body would lean against it in a seated position. However, from what I confirmed in the photos, the door opens outwards and wasn't locked. Thus, the body would fall into the external space the moment it leaned on the railing, so something had to secure the door. Considering this with the fact that all suspects have alibis, a possibility arises: some sort of timed device was set at the entrance."

Risome's eyes once again fell to the murky water surface.

"In other words, the murderer used something that disappeared over time to secure the door, allowing them to escape. Why did this 'something' disappear without leaving a trace? Is there something at the scene to cover the traces? If not, this deduction is wrong. However, coincidentally, there was something that could hide evidence. And that's when the water, paper, and thumbtacks came into play."

Yuzuno recalled again. After Risome's fingers paused on the image of the entrance, he reviewed the photos within the walkway. In the photos, the ground was soaked with crimson water, and paper was scattered within it.

"The scene was full of water and documents, very unnatural. And the thumbtacks were right in front of the entrance. As for their use, they're generally for fixing paper. Another well-known usage is to put them in the shoes of annoying people, but this isn't a ballet class; it's an aquarium..."

Sendou interrupted: "Stop joking. You figured out the murderer used toilet paper?"

"Exactly. Wrap toilet paper around the railing, secure it, then slowly dissolve it with water to function brilliantly as a timed device, all while concealing the traces. I asked my brother, and he said there's an old water pipe leaking above the entrance. Additionally, the victim had a thin build. With a light weight, even paper, when overlapped to increase strength, can fully support it. Ordinary paper is hard to dissolve thoroughly and isn't suitable for overlapping, but there's a great invention in the world meeting all these conditions—a miracle-making tool, toilet paper."

The inventor of toilet paper surely never imagined it would be praised to such heights.

"Of course, these are just hypotheses. However, when I came to the actual site, confirmed the old water pipe was leaking, and discovered paper stuck outside the entrance, I concluded this."

After his explanation, Risome opened a plastic bottle cap and took a sip of cola. The two detectives stood side by side in the narrow corridor, falling into a defeated silence.

"...Did you come up with this just by looking at photos in the car?"

"Yes, and I thought one step ahead as a bonus."

"One step ahead?"

"This is a premeditated, solo crime."

When he hung up, he indeed mentioned this to his brother.

"If there were accomplices, the murderer wouldn't need to use such a deceptive device. They could achieve their goal by alibiing each other and lying. So, it's a solo crime. Moreover, checking the leakage location thoroughly and preparing thumbtacks and toilet paper makes it very likely a premeditated murder."

"Understood, you don't need to say more."

Though Sendou's reluctance was evident, he ultimately conceded. Risome teased him intentionally, "Aren't my words valuable as a reference?"

"Don't get cocky. Whether you're right depends on testing the paper wad. Besides, we already knew it was a premeditated murder. There is a murder weapon."

"Murder weapon? Oh, right, right. It's not inherently part of the aquarium, but brought in from the outside, isn't that right? I can only assume the murderer prepared it in advance."

"That's correct."

Sendou hoped to pick faults but instead received a perfect explanation, so he glossed over it.

"If so, carrying out murder at that time..."

Risome looked into the depth of the walkway where the murder weapon was found, now marked by just a board—and paused.

"...What is it?" Sendou asked. But Risome didn't answer. He fell into complete silence, unclear where his earlier verbosity had gone. The humming of surrounding machines and the sound of dripping water leakage onto the lock became more pronounced, enveloping the entire passageway.

Moments later, Risome took out their phone from their pocket, operated it briefly, and murmured, "There's only one line."

"Huh?"

"I mean the footprint on the wet paper. There's only one line."

Seemingly, he confirmed the crime scene photos again.

"Ah, oh... isn't that the murderer's footprint?"

"Perhaps… but, this..."

Covering his mouth with his hand, Risome sank into silence once more.

After a while, the busy Sendou finally grew bored of waiting.

"Oh, it doesn't matter. In any case, even if it's not strenuous work, I still need to say 'well done.' You can leave now. Hakata, escort them both outside. I'm off to see Azusa."

Sendou gave instructions as he left the walkway alone. His departing figure seemed to age ten years since the beginning. Could conversing with Risome have given him stress?

Despite Sendou leaving the animal keepers' zone, Risome remained at the site, appearing deep in thought. Brother, unable to tolerate it, pushed Risome on the back, ushering him and Yuzuno out of the walkway together. He staggered along, saying, "Brother, can you lend me a notebook?"

"A notebook? Mine?"

"Please! Consider it an advance on your reward."

"…Fine, but you must return it soon!"

Anyway, now that the information is mostly yours—Brother had no choice left, reluctantly handing over his notebook. Risome took it eagerly, reading intently.

"What have you figured out?" Yuzuno asked. Risome replied, "Not figured out… just a flash of inspiration. Right, a flash of inspiration. I have no basis, but maybe… no, I might be wrong."

He stopped flipping through the pages, muttering to himself—

"This makes no logical sense."

[Chapter 4: Meaningful Testimony of the Bathroom Expert]

The task of escorting Yuzuno and others outside wasn't immediately completed by her brother.

The moment they left the walkway, Risome began surveying the animal keepers' area in detail. He moved back and forth around the tank, observed down the stairwell to the first floor, then suddenly traced the footprints he hadn't noted when entering earlier. Confirming the notebook entries, placing his face close to the wall pipe for inspection, then fiddling on his phone with utmost focus.

"Didn't I tell you, I want to go back early..." Yuzuno didn't understand Risome's actions, watching him closely. Brother obscurely asked, "Hey, what do you mean by what you said earlier?"

"What did I say?"

"You said before, you helped him get dressed? ...What's that all about? Was he undressed?"

"Huh?" 

She intended to boast about the effort it took to bring Risome out, not expecting Brother to skewed perceptions.

"Are you involved in that thing? Was it like that? Is that why you were resisting coming here when I called you? Because of this?"

"What an idiot!" 

Yuzuno glared icily at her brother, feeling he wasted his insight on irrelevant matters. Both Sanae and her brother, how can they be like this...

“Nothing of the sort happened! Risome classmate, say something. I didn't do anything, right?”

“Huh? Yeah, you didn't do anything, except break the air conditioning.”

“What does that have to do with the air conditioning...” 

Risome nonchalantly replied, engrossed in his investigation. He turned on the faucet, confirmed no water, murmured repeatedly, “Drip. Water. Blood. Bloodstain. Blood in the drain…” Then he left that area, stood before the mirror for a moment, paused at the angular blood stains, then swiftly moved to the storage closet. Gently peering at items on the shelf and opening the lockers, he suddenly halted, frozen.

“Hey, are you sleepwalking? Is everything okay?”

Upon hearing the brother call him, he turned around and said, “Brother, you guys found a mop and bucket, right? The mop had bloodstains, and the bucket had cracks.”

“…Yeah, wasn't that noted in the notebook?”

“Mop and bucket. I see. How interesting. I see, I see...” 

The brother and sister exchanged looks, utterly perplexed by the repeated “I see.”

Ending his stupor, Risome entered back through the room door into the corridor. Not a single shadow was seen. Each room door was closed tightly. He glanced toward the corridor end and asked, "Everyone related is gathered in the meeting room over there, right?"

“…You don't intend to visit that meeting room before leaving, do you?”

While Risome hadn't expressed such a wish, his silent steps toward the corridor's depths indicated otherwise.

“Hey, stop there! I told you to stop! What do you plan on doing?”

“I have to confirm a few things with the Director and Kaori.”

“Then tell me, and I'll ask them.”

"No, no, how could I trouble Brother?"

"The current situation is what's troubling me... enough, it's with the Director and the newspaper club people, right? You wait here."

Successfully blocking Risome at the office doorway, Brother went alone into the corridor's end "Second Meeting Room" and promptly brought out the witnesses.

“Oh, Tenma! And Yuzuno! Wow, you both came!”

It had been two days since hearing the school newspaper president's vibrant voice. As soon as Kaori saw Yuzuno, she ran toward her, appearing ready to embrace her. Just as Risome expected, she was perfectly fine.

“Oh, it’s great you’re here! Now the case will surely be solved.”

“You’re too excited, calm down a bit!”

“Ah, sorry, sorry, but it’s really scary. Seeing you two really boosts my spirits!”

"Please don't be more spirited than you already are."

Following were a man with a mustache wearing a dress shirt and two newspaper club members. That was Vice President Kento Kuramachi and Yuzuno's classmate Taka Ikezumi. On seeing Risome, Kuramachi shouted "Wow—" while Ikezumi on seeing Yuzuno.

"It's really Risome. Kaori said you'll come, not jokingly, it seems.”

“I didn't want to come. By the way, who are you?”

“I'm Kuramachi, from the next class, vice president of the newspaper club. Don't you know me?”

“I forgot.”

"How rude... well, it doesn't matter."

“Aren’t you Hakata? What are you doing here? Hakata, are you also a detective? Oh, are you perhaps an assistant?”

“No, somehow I found my way here…”

“She’s uninvolved. Risome isn’t a detective either.” 

Brother carefully rectified beside them. Then addressed the bearded, confused, clueless gentleman.

“This is it. He counts as a consultant for the investigation. Not a suspicious person, please rest assured.”

“Oh…” 

Even so, there was still suspicion. The gentleman furrowed his brows, exhibiting caution.

“The solver of Kazekozan High School's murder case was him.”

"Huh? I see... so young, truly remarkable..."

He seemed to have learned about the Kazekozan case on television. He gazed at Risome, highly impressed. Brother's face twisted beside him, likely regretting said too much.

Risome himself, however, remained indifferent to others' views, directly addressing the man: "Nice to meet you, I’m Risome Tenma.”

“Oh, hello, hello! I’m Director Nishinozu."
The gentleman introduced himself politely.

“Pardon my abruptness, but I wanted to ask, do all the zookeepers here wear yellow polo shirts?”

He was indeed acting abruptly. Director Nishinozu answered awkwardly, “Yes, that's our uniform. Everyone wears it except for those in administrative roles.”

“Are these provided by the aquarium?”

“Yes.”

“Then, how many rooms in this back area store these polo shirts?”

“……”

His questions became increasingly puzzling.

“Are you talking about new polo shirts?”

“Old ones are fine too.”

“If that's the case… there are a few spare ones in both the men's and women's changing rooms. Also, there are new ones prepared for distribution in the warehouse on the first floor.”

“The warehouse. I see…” Risome turned to his brother, “Brother, the warehouse is also under camera surveillance, right? No one was caught going in?”

“Yes.”

So what? — He couldn't continue to ask, for Risome had already turned to Kaori.

“You met with the staff immediately at the shark tank after the incident, right? Was there anyone suspicious?”

“Suspicious? Like?”

“For example, someone with disheveled hair or wet clothes.”

The newspaper club members checked with each other and confirmed they hadn’t noticed anything like that.

“But, the staff's situations were captured in the photos, so maybe something can be found.”

“Oh, I’ve already seen the photos. There was nothing strange. I just wanted to confirm with you guys.”

Risome nodded and asked the director another strange question.

“By the way, is there a restroom in the back area?”

“Restroom? Yes, turn at that corner.”

“I’ve seen the diagram, so I know where it is. What I want to know is the type of toilet paper.”

“Type?”

“Most recent toilet paper has perforations for neat tearing. Does the toilet paper here have those?”

“Per-perforations? Um, I’m not sure about that…”

He crossed his arms with a troubled expression. Even a director wouldn’t know such minor details, right?

“Yes, they do have perforations.”

The answer came from an unexpected place. It was Kuramachi from the newspaper club who answered.

“…How do you know?”

“Because I used the restroom before the incident.”

“Oh, really? Great, what a stroke of luck!”

Risome cheered, almost shouting hooray. His brother, already used to his odd behavior, calmly said, “Can you explain what this is about?”

“The culprit used the toilet paper at the scene. If you remove toilet paper from the roll, it gets scrunched up and loses strength, so the culprit probably brought in an entire roll. However, if they were caught with such an item after the incident, it would arouse suspicion, so they had to hide it. Besides, in this building, the place where toilet paper won't arouse suspicion is pretty obvious.”

Hearing this, Yuzuno finally understood. Where would it be most natural to hide toilet paper used to set up a trick? In the restroom, of course.

“That part I understand. But what’s the significance of the perforations?”

“The toilet paper the culprit used for their trick likely didn’t have perforations. Perforated toilet paper could break at the perforation. The toilet paper here has perforations, so it couldn’t be used for the trick. This means, like the knife, the culprit would likely have prepared non-perforated paper in advance. If the culprit then hid it in the restroom…”

“…It would clearly stand out from the other toilet paper, making it easy to find. I see.”

“Amazing! It's just like a detective!”

Hearing the conversation between the two, Ike’s eyes lit up. Kaori, feeling inexplicably proud, said, “Yeah, yeah!”

“But, using toilet paper to set up a trick… what kind of trick is that?”

Yuzuno briefly explained the situation where the culprit forged an alibi. Ike shouted in excitement once more, “Amazing, amazing! You're like a detective!” He was a boy whose heart and appearance were equally innocent.

However, the problem was that this "detective" was equally excited.

“Let’s go quickly, brother, let’s hurry. The evidence is in the restroom!”

Risome tugged at his brother’s sleeve, waving to the director and incidentally bringing Yuzuno and the newspaper club members along. The seven-member team moved through the narrow corridor.

Risome was like the Pied Piper, and Yuzuno and the others turned into mice.

Turning the corner where Kaori and others had appeared from, there was a door marked “Archives” and a staircase, though not the one Yuzuno and the others had come down. Opposite that was a double door marked “B5·Lemon Shark,” which seemed to lead to the zookeepers' work area. Passing through here and reaching the end was the men's and women's restrooms side by side.

The man at the front entered the men’s restroom first. Yuzuno hesitated for a moment but then thought, since there was no one inside anyway, and pushed open the blue frosted glass door.

The scent of lavender hit as soon as she crossed the entrance. Inside the restroom was a washbasin with a mirror and a trash can next to it. The wall had two urinals, and there was a cubicle. This was a small restroom used solely by staff. However, it was very clean; even the gaps between the blue tiles remained white without apparent dirt.

Risome’s target was, of course, the cubicle. He opened the wooden door, and inside, on the floor, was a squat toilet. On the right-hand wall, a rack held a half-used roll of toilet paper. A triangular shelf was mounted close to the ceiling on the left corner, holding new backup rolls and a purple air freshener.

Risome took down the toilet paper from the rack, rotated to examine it, then took down the backup roll from the shelf for comparison before concluding, “This is it. Brother, I've found it. This is the roll the culprit used.”

“Huh? Already found it?”

He held up the roll taken from the rack. Finding evidence in less than ten seconds seemed a bit anticlimactic for his brother.

“No doubt about it. No perforations, and it’s slightly narrower than the one on the shelf. And, crucially, look here, this might be a bloodstain.”

Six heads leaned in together, all focusing their gaze on the partially used roll of toilet paper.

“The thickness is about four centimeters around the cardboard tube. Indeed, there are no perforations, and compared to the new roll in Risome’s other hand, it is indeed slightly narrower, even if only a bit. 

Moreover, one side of the roll had faint black markings.

“Really, it is! But for the culprit to boldly place it on the rack like that…”

“If a partially used roll of toilet paper were placed among backup rolls, wouldn’t that be strange? Placing it openly on the rack is best.”

They had already been briefed on the trick before coming here, so they immediately understood. However, anyone using the restroom without prior knowledge probably wouldn’t notice the subtle differences in the toilet paper. The black marks on the side would also be hidden by the rack and unseen.

“After the incident, someone used the restroom and flushed the paper away… thereby naturally destroying the evidence.”

“Exactly. That’s what the culprit hoped for.”

Kuramachi, though just having learned the details, quickly used his agile mind. Risome nodded in agreement and said, “Because a trick was set up, only this much toilet paper remains.” 

Yuzuno blurted out, though she got knocked on the head with a roll of new paper for it.

“Silly, you could never use that much. Didn’t someone say earlier? This was already prepared by the culprit, so it wasn’t much to begin with.”

“Huh? Isn’t more better?”

“If the paper roll were too big, it wouldn’t pass through the bars when winding. The gap between the bars is only about ten centimeters.”

Oh, I get it. He had measured the gap between the bars.

“Wait! The thickness might actually be the key here.”

Risome tried stuffing the suspicious roll of toilet paper into his pocket. However, even though half-used, the roll was too thick to fit properly.

“It won’t fit.”

“…What are you trying to prove?”

“I’m saying this roll won’t fit in a pocket. This is very important, brother. Very important!”

For unknown reasons, Risome’s attitude suddenly changed, praising Yuzuno, “Well done, Miss Hakata!” Though he hit her with the toilet paper again, this time on the shoulder instead of the head.

Then he asked the silent director, “Mr. Nishinozu, do the zookeepers in this aquarium clean the work zones themselves?”

Another sudden and inexplicable question.

“Yes. It's mainly done by the person responsible for the tank.”

“Mainly? So there are exceptions?”

“We have a small staff here, so it’s common for available personnel to clean on behalf of others.”

“Do clerks sometimes clean for the zookeepers?”

“Yes. If it’s just cleaning, sometimes clerks do it. Even I’m often used as an assistant.”

Nishinozu smiled wryly.

“Besides cleaning, zookeepers also have many other tasks. Are there times when clerks help with those?”

“…No, definitely not. Feeding and tank preparation work, though sometimes zookeepers help each other, isn’t given to clerks. It requires expertise.”

“True enough. Another thing, people working in the zookeeper area usually wear gloves, right?”

“Yeah, most do wear gloves.”

“Understood. Thank you! Your responses were excellent.”

Risome bowed deeply. After all, he didn’t slap the director’s shoulder with the toilet paper.

“In any case, brother, this is up to you now. Please have the forensics department do a detailed examination. So now the question is…” he handed the paper roll to his brother, glanced at the cubicle again, then aimed his question at Kuramachi, “Is this the cubicle you used before the incident?”

“Yes, I went in around 9:40 and came out around 9:45.”

“9:45, huh. Just before the incident. Was there any change apart from the toilet paper on the rack?”

Risome stepped back, and Kuramachi entered the cubicle, glancing around in this small space. Then he shook his head, saying, “I don't think so.”

“And no changes with the backup toilet paper?”

“Hmm. When I went in, the paper on the rack was nearly used up, so I checked the supplies on the shelf. I remember the air freshener was facing me with its back, so I didn’t know the brand. I don’t think anything’s changed.”

“No changes… hmm. You said the rack’s toilet paper was almost used up. What happened in the end? Was there enough?”

“Enough. About five or six segments were left.”

“Did that roll have perforations?”

“Yes. And I even thought, since I was borrowing the restroom, I should make sure to tear it neatly and nicely.”

Extraordinary memory. This impressed even the questioner.

“Amazing. A true vice president of the newspaper club, able to assist such a president.”

“That’s just my hard work.”

“Hey, hey! What do you mean by ‘such’? Besides, I didn’t make you work hard!” Kaori interjected to stop their conversation.

“But, Kuramachi, you really are quite impressive. Especially active!”

“Yes, his testimony was significant! I bestow upon you the title of ‘Toilet Genius,’ no, ‘Restroom Scholar.’”

“No, I’ll pass on that…”

“You can use ‘The Seven-Year Ultimate Move’!”

“…What is that?”

Kaori began explaining the mysterious skill, while Risome turned to inspect the trash can beside the washbasin. After a glance, he simply said, “It’s empty.”

After confirming, he immediately left the restroom. When Yuzuno and her brother caught up to him, he was about to enter the pink door next to it.

“Yo, hold on a second!”

“What?”

“That’s the women’s restroom.”

“I know. Since there’s nobody in anyway, you went into the men’s room too, right? Stop complaining.”

“Ugh…”

With that retort, Yuzuno was left speechless. She decided to follow him, at least to keep an eye on him and prevent mischief. Ike and Director Nishinozu also followed but stopped at the door. They were two gentlemen who knew their manners.

The women’s restroom, like the men’s, was small but immaculately clean. The washbasin, trash can, and three cubicles were inside. Risome checked the trash can first; it was empty as well. From the side, he didn’t look much different from a weirdo.

“What are you searching for?” asked his brother hesitantly.

“When Kuramachi used the restroom earlier, the paper on the rack had perforations and hadn’t been finished. But now, after the incident, it’s replaced with what the culprit prepared. I’m looking for the original roll. The backup rolls in the men’s restroom all have cores, which means the paper here should also have cores. Loose paper can be flushed away, but the tube is not that easy.”

While he answered, Risome continued examining, pacing back and forth in the women’s restroom. The structure of the three cubicles was the same as in the men’s restroom. The paper on the racks all had perforations like the new ones, and there was no anomaly among the backup rolls.

“If the culprit replaced the toilet paper, they must’ve discarded the core. But… it’s not here.”

He closed the door of the third cubicle and stood still in the center of the restroom—oh no, that was indeed dangerous.

“Alright, alright, let’s leave for now. The police will find the original roll.”

His brother nudged him forward, attempting to guide him out.

“You already found the roll used in the crime. Isn’t that enough?”

“No, without the core, it's not logical. If it's not here, then where could it be…”

“Hey, can I say something?”

Yuzuno suddenly raised her hand, interrupting Risome. “...What is it?” he asked.

“Maybe the culprit is a man.”

After learning about the toilet paper switch, she thought of this through the door’s frosted glass as she saw the red female symbol.

The culprit replaced the men’s restroom roll. In other words, they could enter the men’s toilet smoothly, being a man?

Though Yuzuno guessed it this way, Risome said, “A man? Can’t be concluded right away, right? Are you deciding he’s a man just because he swapped the men’s roll?”

“Ugh…!”

He hit the mark in an instant.

“You can see if the restroom is empty from the entrance. Swapping a roll takes only a few seconds, so a woman could also enter the men’s restroom if she aimed for when no one was there.”

“But even though there’s a women’s restroom…?”

That part I understood—his brother chimed in, “The men’s entrance is right in the corridor's blind spot, while the women’s faces it. To be safe, the culprit was cautious to avoid being seen entering or leaving. Right, Risome?”

“Exactly.”

“That’s, that’s…” Yuzuno retreated, leaning against the wall.

“I… I was refuted by brother…”

“What’s that supposed to mean? Aren’t I supposed to refute you? I am a detective, after all!”

“‘Supposed’ is not enough, you know.” Risome muttered low, pushing through the door. In the corridor, the two gentlemen waited as before. Behind them, Kaori continued explaining the “Seven-Year Ultimate Move” to Kuramachi.

“Find anything?” Kuramachi ignored Kaori’s explanation and asked.

Risome shrugged, “Nothing at all… Mr. Nishinozu, do the staff also clean this restroom?” 

“Yes.”
Recently, it's been the part-time worker Honoka Nishikawa doing it." 

"I see the storage cabinet for cleaning supplies and the place for storing spare items aren't in the restroom. Where are they?" 

"All those things are also kept in the warehouse on the first floor. Supplies, spare items, everything is there," came the same response as before regarding where the polo shirts were.

Risome pondered to himself, looking up at the ceiling, "That's no good. This means it has nothing to do with the restroom. If that's the case, what happens? If so... Oh, right."

His posture briefly stiffened, but quickly, as if enlightened by a revelation, he suddenly straightened his neck and, leaving Yuzuno and the others behind, started running down the corridor, heading directly for the conference room.

His brother immediately shouted, "Stop! Stop!" and caught up with him saying, "You can't just act on your own! I'm begging you! Where are you planning to go?"

"I need to go to the suspect again. I have something to ask."

"I told you no! I'll go ask; just tell me the question."

"No, the question involves minute details, so I need to ask directly if possible... Hmm?"

Though they were close to the conference room, they stopped in their tracks. The door was slightly ajar, and they could hear voices inside.

"—So, are everyone's testimonies correct?"

"I said they're correct, didn't I? Jeez, all the alibis are valid, so why the double-check?"

The hoarse voice belonged to Sendou. It seemed he had arrived at the conference room a step ahead of Yuzuno and the others. The back-and-forth voice was a rough man's voice. Kaori mumbled, "That's Daitabashi."

"Here's the thing, the previous alibi has lost its significance."

"Could it be that the alibi scam of the killer has been exposed?"

Another voice, pretending to be humorous, rang out. Ikezumi commented, "That's Mr. Jiro."

"Speaking of which, you all aren't completely trustworthy either. Just now, a few strange little ones were wandering in the corridor back and forth."

"…Strange little ones?"

"I saw through the glass on the door. Two little guys I hadn't seen before, with the detective, director, and someone from the newspaper club walking in the corridor. Who are they? Isn't this area supposed to be sealed off?"

The people in the corridor exchanged glances. The brother's efforts were all in vain. Risome's presence had long been exposed, and along with it, Yuzuno.

"Um… Hold on a second, was there someone called Tama in the corridor? With the director and others?"

"Ah, yes. Anyway, first tell us who that is?"

"Oh... that person..."

"That person is me."

Risome suddenly pushed open the door, causing a minor commotion both inside and outside the room. The owner of the rough voice pointed and shouted, "Ah, you... it's you! You!"

All the brother could do was hold his head in silence.

There was no choice; Yuzuno and the others had to follow him into the room. The long table had been moved to the back of the room, and about ten people were sitting in side-by-side chairs. A plump middle-aged woman, a bald old man with wrinkles all over, a man in a shirt with some stubble, among others, all were faces seen in the on-site photos Kaori had taken.

In front of them stood Sendou, Azusa, and several guards responsible for monitoring. Sendou, though he saw Risome, seemed too drained to scold him and merely shook his head, saying, "Give me a break."

"Hello, everyone! My name is Risome Tama."

"Hello nothing! What are you doing here?"

Confronted by the leisurely greeting from Risome, a muscular man, Daitabashi, seriously started questioning right away.

"I heard he's something like an investigation consultant," Nishinozu nonchalantly introduced. It seems the director's words were convincing enough for the staff to murmur "Huh?" A long-haired man leaned forward and asked, "So you're a detective, huh? Ha, interesting. Is that girl your assistant?"

"We're neither detectives nor assistants, but you can call us whatever you like. You're Mr. Jiro, right? The one who snuck off to the archive?"

"…"

The man Risome pointed out was caught off guard and froze.

"I recognize all the rest of you too. The curly-haired one is Ms. Mizuhara, in charge of display design. The older gentleman looking for a notebook is Mr. Shibaura. You're Mr. Daitabashi, right? And the chubby one is Ms. Izumi."

"Y-you're so rude!"

"Sorry, my mistake. And, dressed in navy, you're Dr. Midorikawa. The short-haired young man is Mr. Oiso. Oh, and there's Mr. Fukamori, who is responsible for the sharks..."

He fluently recited the names of each staff member. During the phone call in the car, his brother hadn’t introduced everyone's appearance in detail. Presumably, he had read his brother's notebook and memorized it all in a short time.

However, for those staff members who knew nothing of the situation, a suddenly-arriving teenager claiming to know them and accurately stating their names, duties, and even particulars of their alibis, could evoke nothing but astonishment and fear. After Risome called out everyone's names, all the curious glances turned to looks of dread. Even Sendou and Azusa, standing by, were left speechless.

"…So, regarding why I'm here, it's because I have one question to ask everyone. Just one question," he glanced around the room, cutting straight to the point after his trust-winning performance, "May I ask if any of you used the men's restroom after 9:45 this morning?"

That was all he asked. But no one raised their hand.

After a while, Ayase, the bespectacled woman, said, "…Is the restroom important?"

"It's extremely important. However... it seems no one has used it. But that's okay; I understand. Thank you!"

He nodded simply and left the conference room. It was so straightforward it almost seemed anticlimactic. Yuzuno, Kaori, and the others, along with Hakata, also exited the conference room. Sendou and Azusa followed.

"S-Sendou Inspector, I'm sorry. It's not like that; there was a reason. Risome said he was looking for the toilet paper the killer used, so..."

His brother hurriedly explained why Yuzuno and others hadn't been sent away, but Sendou didn't seem to care. It appeared something more serious than Risome's presence had occurred. Not just him, even Azusa seemed to have aged ten years.

After closing the door, Sendou sighed, his voice dripping with fatigue, "This is a real mess now."

Referring to Risome Tama's deductions, they temporarily ignored the alibi at 10:07. Thus, the issue reverted to the period before this time. Amamiya was unmistakably alive before 9:50. Therefore, the time frame in which the murderer could have committed the crime was the 17 minutes between 9:50 and 10:07. Referring—only as a hypothesis—to Risome's idea that "the killer left at 9:57," the most suspicious window of time would be from 9:50 to just before 10.

Comparing that with the testimonies of each suspect—

Takako Izumi: From 9:50, she was alone organizing documents after Amamiya and Takino left the zookeeper's room until after 10:00.

Takahiro Funami: From when Mizuhara left the office at 9:50 until after 10:00 when Jiro returned, he was alone checking financial records.

Jiro Tsutou: Went to the archive around 9:50, took a break for about 15 minutes. Returned to the office earlier than Izumi and Ayase but was alone during his break.

Yuko Ayase: After introducing the school newspaper club member to the director, worked alone in the director's office from 9:50 until after 10:00. Around 10:02, went to the office to make coffee.

Tomoka Takino: Went to the women's changing room to look for a dog whistle at 9:50. Was called by Mizuhara near the exhibit workspace before 10:00. Alone the entire time.

Riki Mizuhara: Went to the exhibit workspace at 9:50, worked alone. Called out to Takino near 10:00.

Kanguro Daitabashi: Headed alone to the first floor of the zookeeper workspace at 9:40 to feed the tanks. Finished around 9:55 and went to the infirmary.

Mitsuhiko Midorikawa: Went to the first-floor infirmary at nearly 9:40. Alone until Daitabashi arrived near 10:00.

Kai Oiso: Around 9:40, went to the first-floor feed preparation room. Since Shibaura returned to the second floor immediately, worked alone until 10:03.

Tokuro Shibaura: Went to the feed preparation room with Oiso but went to the men's locker room on the second floor because he forgot his notebook. Stayed alone in the locker room until returning at 10:03.

Honoka Nishikawa: Started cleaning the corridor alone around 9:40. Although there are multiple eyewitnesses, her actions remain unclear between 9:50 and when she was filmed by the camera at 10:03.

Therefore—

"At least between 9:50 and around 10:00, not a single suspect has a clear alibi."

Sendou concluded the report. He looked too tired to even stand, leaning against the wall halfway through his speech.

"So the suspects are still at eleven?"

"Yes, from zero back to eleven."

"Hmm..."

The wrinkles between his brother's eyebrows deepened. It seemed more confusing than when he called.

A case where no one could possibly be the killer turned into a situation where anyone could be the killer. Risome's sorting of alibis resulted not in narrowing the scope of the investigation but in expanding it to the limit.

The eleven staff members acted separately within a confined space. Some were too busy, some driven by a habit of slacking off, and others due to warmly caring for their juniors.

"As a result, we're still at a standstill."

The groan from his brother represented the feelings of all the investigators. However, standing beside him, an unrelated individual was exceptionally excited. He said: "But, we've also made a discovery."

"…Risome."

"What, Officer?"

"Why are you still... okay, enough, fine. What did you discover?"

"Even if I tell you, it will only be considered a reference."

"Hurry up and say it!"

Inspector Sendou's temper seemed to reignite, restoring his natural vigor.

"Solo crime has been confirmed, based on similar deductions from before. If it were a group crime, they should've already fabricated alibis in advance. Even though there may be very cautious killers who would install timed tricks to create alibis even with a co-conspirator providing false testimony, failing to fabricate an alibi—or not having an accomplice affirming you're absent at critical times—doesn't make sense. Such accomplices are meaningless. Therefore, since not a single person has an alibi during the presumed time of the crime, it's concluded as a solo crime."

"Oh, so that's it."

"So that's it—those words go too far. A solo crime means it's a simple one-eleventh probability. Establishing this... investigating various methods...”

"Enough," Inspector Sendou interrupted him again, "I get it, that's enough, good job, you can go back now, Sakasaka-san, you can go back too. No more causing trouble for us."

"But..."

"I said go back, so go back!"

This time, Inspector Sendou's voice reached its maximum decibel level of the day. After speaking, he realized they were in the center of the corridor. He took a glance at the second conference room, knitted his brows, and lowered his voice, "Your work should be done, right?"

The contract only covered sorting out the alibis.

He nodded knowingly, saying, "Yes, I get it. It's just in time for the re-broadcast of 'Nadia,' so I'll head back."

"…Yes, there's nothing more now. As long as you go back, that's fine."

"But I, as a consultant, have one final piece of advice for you."

"I told you to leave..."

"If it were me, I would investigate the changing room. Well then, goodbye."

He waved his hand and walked toward the west side stairs. Yuzuno and the members of the newspaper club followed him, with his brother bringing up the rear. His brother received a stern order: "Make sure to send him off this time!"

Watching them leave, the expression on Sendou's face was like seeing off a plague god.

In the exhibit area, Kaori complained to his brother, "He called us over, and now he has such a nasty attitude?"

"Yeah, it's not good."

"…Is that an apology or agreement from you?"

"Both."

They passed through the hall with the jellyfish tank and headed toward Building A. His brother's pace remained quick.

"Brother, you don't have to apologize. I recorded 'Nadia.'"

"I'm not talking about that... Inspector Sendou is upset because your presence was revealed to the staff, so he's uncomfortable. Because he initially wanted to keep it as secretive as possible."

"Well, that's all Risome's fault for acting on his own."

"It didn't matter in that situation; it was already exposed anyway."

Risome showed no sign of regret.

"Even so, didn't you have to burst in suddenly..."

"Because I wanted to ask about the bathroom question."

Regarding who used the bathroom, not a single person answered, and he himself immediately said, "I understand" and gave up—however, "More important than this, what your brother needs to do is investigate the changing room. Investigate every corner. I'm especially interested to know if there are any signs of blood."

"…Alright, alright, I'll check. But, what exactly have you figured out?"

"I'm currently in a subtle phase of not knowing if I've figured it out. But there have been many discoveries."

Kento directly asked behind him: "What exactly?"

"At least I know what to use as a clue."

"A clue? Toilet paper?"

His brother pressed for details. Risome looked sideways at the reef tank crawling with wrasse and succinctly answered, "—The mop, the yellow-handled mop."
Chapter 4: A Sunday Date and Experiment by the Water

1. The Mop Knows Everything

Early on the second day, three unimaginable things happened consecutively.

First, despite it being a rare Sunday without training, a free day of rest, Yuzuno inexplicably found herself in Risome's room, perhaps due to having too much free time.

Second, the room owner, whom she assumed would still be asleep, was already up, dressed neatly, and not only was he off his bed, but he had left the room and was cheerfully mopping the corridor.

"Oh, isn't this Miss Hakata? Good morning."

Moreover, he actually greeted her.

"I mean, you're Risome-kun, right? … Is it really you?"

"You must be a morning muddlehead seeing hallucinations."

"Why are you up so early... Ah, did you stay up all night? You're heading to bed now, aren't you?"

"I just got up, how could I sleep? It's nine-thirty now!"

"Wow, a common-sense answer..."

Then the third event occurred.

"I don't know why you came here, but I was just about to head out."

"… Uh, sorry, I think my ears might be malfunctioning. Did you say you're going out?"

"Yes. Are you alright?"

"Where, where to? Akihabara?"

"The Aquarium. Going to investigate a case."

"A case, a case..."

The shock was so overwhelming for Yuzuno that she involuntarily leaned against the door of the Hundred Poems Association. Risome taking the initiative to solve a case was unimaginable. It seemed yesterday's bizarre behavior wasn't a mere whim after all.

Even after being kicked out of the aquarium, his actions hadn't ceased. He took the newspaper club members to a nearby café to gather details about the pre-incident circumstances. Even while being driven back by the patiently waiting Hatori, he refrained from fiddling with his phone and remained deep in thought.

By the way, Yuzuno stayed with him the whole time but managed to catch the last moment of the competition. Kazekozan's performance was quite satisfying; in the individual competition, the captain won second place, and in the team competition, although they lost to Hiten, they defeated Tang’an to secure second. They celebrated at a pancake shop in front of the station and returned in high spirits. In her closing remarks, Captain Sugawa said: "Everyone worked so hard during the first half of summer, so we'll take two days off starting tomorrow." The tired team members applauded in agreement... Sigh, who would have thought that she'd waste the precious first day of her long weekend from early morning in such a place.

"What's wrong with you? Weren't you saying yesterday that it was troublesome and you wanted to come back early? Haven't the rewards been decided?"

"I got a bit interested. When I'm interested in something, I give it my all."

"Ah, I know that."

The mess in the room clearly demonstrated that fact.

While that was the case, what aspect of the case actually piqued his interest? Was it the bizarre fact of a shark eating the victim?

Although it wasn't clear yet: "Anyway, this is better than sleeping. You got up early, how impressive!"

"Getting up early on Sundays is basic."

"Hey, hearing that from Risome-kun's mouth..."

"It's because I want to watch Asahi TV's 'Pretty Cure'."

"Huh?"

The previous sentiment immediately turned cold. No, there was no need to dwell on the reason at such a time.

"Yeah, if you don't apply pressure, it just won't work."

Risome raised the mop and muttered. Yuzuno had thought he was mopping with water, but upon closer inspection, noticed something odd. The concrete floor under the mop was scattered with paper shredded by water.

"You're not cleaning?"

"Who would do something that only a widow would do? I'm experimenting to verify whether fibers stick to the mop."

He placed the mop against the wall and observed the paper on the floor.

"With a little pressure, they stick. Conversely, without it, they don’t. If you exert force, the paper below becomes tattered. So far that's all I've discovered."

He concluded the experiment results solemnly. Now that he mentioned it, when he left yesterday, he did say the mop was a clue...

"In short, the mop was brought to the hallway by someone, and that's clear. But the problem lies with the killer pressing down the mop. Pressing down... and it's exactly as I imagined, but..."

Mumbling incomprehensibly, he glanced at his watch and muttered, "It should be soon. Goodbye, Miss Hakata."

He waved and headed towards the north gate, leaving the mop leaning against the wall and the sticky paper on the floor, typical of Risome's disregard.

"Ah, hold on, I'm coming too."

Yuzuno ran after Risome. Both his statements from yesterday, his enthusiasm today, and the experiment just now were all beyond comprehension, indeed leaving a bad feeling. Initially, her early visit was to understand the intention behind his behavior from yesterday. Walking beside him, she wasn't met with any disdainful looks.

"You can come with me, but don't interfere."

"When have I ever interfered with you?"

"You were the one who broke the air conditioner, weren't you?"

"You're bringing up the past...! That was obviously your own fault."

"I was living quite comfortably in the room."

"It's your lifestyle that's the problem. And the living space too..."

"Hey, hello there, good work!"

The abrupt greeting wasn't aimed at Yuzuno, but at a man waiting at the north gate.

A well-fitted suit and an impatient, displeased expression. It was Hatori, the rookie from the investigation division, present for pickups yesterday. The familiar car was parked beside him.

"Sorry to drag you out early on a Sunday. I'll rely on you again today."

"Why do I have to do this..."

"Please drive safely. By the way, I hope the air conditioner is working properly?"

"Why, do I have to do, this..."

Yuzuno felt he had only uttered this line since yesterday. 

Hatori sulkily signaled with his thumb for them to get into the back seat and took the driver's seat himself. Yuzuno, like yesterday, squeezed into the car, seated behind the front passenger seat, and quietly asked Risome, "Did you specifically call him?"

"I just contacted your brother and he surprisingly agreed to have him pick us up easily."

"There's no hurry today; taking the train would be..."

"Isn't it better to travel comfortably and quickly?"

A refreshing chill permeated the car, chilling Yuzuno's legs exposed outside her uniform skirt. Risome was evidently satisfied with the AC today, just like before.

Risome, relaxed and laid-back. Hatori, resigned and sulky. And Yuzuno, wavering between being speechless and relieved. The second day's journey began with each of them holding differing moods.

He surprisingly had the car stop at a convenience store entrance, purchased oolong tea and a sweet red bean rice ball, and munched away in the cabin, disregarding the grains falling.

"Is that breakfast?"

"Yes."

"Sweet red bean rice... did something good happen?"

"I just like it."

"Such an old man's taste you have."

"You weren't also buying chicken katsu sandwiches to win the competition for yourself? Criticizing me."

Risome stubbornly packed the trash into a bag and took his smartphone out of his pocket.

"I already said it was just by chance."

"Is that so? I thought maybe you were aiming for a huge victory bonus — the timid me will prevail thrice!"

"... What do you mean?"

"Chicken means coward, so chicken katsu sandwich means coward wins thrice."

"Coward, wins, thrice... Ah, I see."

"... That's quite interesting."

"Shut your mouth and drive!"

As soon as Hatori chimed in, Risome snapped at him, once more filling his face with displeasure. Though he finally said something other than "Why do I have to," he was indeed an unfortunate man.

"But it is interesting, indeed moving. I'll proudly eat chicken katsu sandwiches next time."

"Glad to hear it."

Risome chimed while tapping the touch screen, causing the electronic sound.

"What are you doing?"

"Video call."

"Online call? With whom?"

He didn't respond but instead directly showed the screen to Yuzuno. It displayed phone icons and a flashing "In Call" sign.

A moment later, an up-close face appeared on the screen, it was the eldest son of the Hakata family, who failed to return home last night — Yuzuno’s brother.

"Hey! Risome-kun? Hey... can you hear me? ... Ah, Yuzuno?"

"Brother, what are you doing?"

"I should be asking you that! Where's Risome?"

"Here, brother!"

Risome adjusted the screen angle slightly towards himself, waved at the camera.

"Are you using a computer? Nice, the picture's clear."

"Oh, is that so? However, you really chose a troublesome way to communicate."

"I wanted to see your face. Can you hear me?"

"There's some noise, but I can barely make it out."

"We are on the road, so please bear with it somewhat. Oh, thank you for sending someone to pick us up."

The two were conversing casually, leaving Yuzuno entirely in the dark about the situation.

"Hey, why are you talking to my brother?"

"Because we're friends."

"Answer me seriously!"

"I asked him to send a car to pick us up as a condition for sharing my findings. I also wanted to collect information."

Even with the serious answer, Yuzuno was clueless about the entire situation.

"Why is even Yuzuno with you... Never mind, I won't ask. Risome-kun, can you tell me what you found?"

"You should first share what's going on your side. How about the locker room search and the results from the scene's paper and blood?"

"Oh, the results just came in. The blood at the scene was all Amamiya's. The fibers on the mop and shoes undeniably matched the hallway documents. However, the paper stuck on the railing was the same as the toilet paper found on the men's restroom stall. That one's thanks to you... Although several blood reactions were found in the locker room..."

"Oh, did you find something?"

"But upon closer examination, it was fish blood."

"Fish? Oh, of course, it makes sense in an aquarium."

"Turned the place upside down, and nothing's wrong. Didn't find Amamiya’s blood anywhere in the locker room."

"Neither in the men's nor the women's restroom? I see..."

Risome stopped responding and gazed at the scenery flowing past. Yuzuno gradually pieced together the situation.

This morning, Risome contacted her brother, requesting, "I'm going to the aquarium; please send a car." Her brother, naturally reluctant, insisted, and Risome subtly hinted he had "discoveries" that could help solve the case. Her brother agreed, while imposing a condition: "I'll send the car, and you tell me your findings." Risome also wanted information from her brother, so he agreed, saying, "I'll contact you once the car arrives." Then they found themselves in the current situation. At least, that seemed to be the case, yet the reason for not making a simple phone call remained elusive.

"It's your turn to talk about your findings."

Her brother’s face, wearing earphones, positioned closer, expanded across the screen.

"No need to rush, brother? Today is Sunday, let's take it easy."

"How can I not rush? I'm in the middle of... working."

He immediately switched back to whispering, carefully checking his surroundings, appearing to evade someone.

"I'm at the Iso Police Station’s investigation headquarters now. If Chief Sendou catches me doing this with you, he'd kill me. Hurry up."

"That indeed requires utmost caution."

"It's tough for your brother," Yuzuno remarked.

"You're treating this like it's none of your business, huh?"

Her phony sympathy couldn't fool a detective.

"So what's your discovery? You mentioned mops and such yesterday."

"Oh yes, the mop, and the bucket. Since the mop and bucket bear blood and paper fibers, they must've been taken to the murder scene, right?"

"Of course."

"Because of this, I wondered why the culprit necessary had to take these two objects inside."

Risome leaned against the door, propped his face with his hand, occasionally turning his brother’s face on the phone screen towards Yuzuno, starting his deduction:

"Amamiya Shigeru’s behavior on the day of the incident was clearly different from usual. As I mentioned yesterday, this was a premeditated murder. Based on this, it can be inferred the perpetrator lured him to the shark tank. In that case, the perpetrator was waiting for him in the hall, or conversely, Amamiya was there awaiting the perpetrator's arrival. Regardless of who awaited whom, they must've met in the hall. And it became the murder scene. Understood?"

"... Uh-huh."

"So, for committing the crime, two essential tools were needed. These were tools prepared by the perpetrator, what do you think they were?"

"Isn't it a knife and toilet paper?"

"Exactly. The knife was for murder; the toilet paper was indispensable for fabricating an alibi. The perpetrator took these two items to the hall, and so managed to execute the crime."

"Sure, naturally."

"Now then, how did the perpetrator bring these items in?"

"Uh...?"

"If it was just about bringing things into the staff working area, they could've easily been stashed on that chaotic shelf from the day before. But to then bring them to the hallway, what to do then? As I mentioned earlier, the perpetrator and victim probably met in the hallway. And there by the shark tank, nothing else was there, the view was unobstructed, a place that wouldn't hide anything. Approaching Amamiya with odd items like a knife and toilet paper would naturally alert him. What to do then?"

Risome’s pointed and provocative words finally sparked the keen insight of a detective in his brother's eyes. He bowed his head in thought, then said: "... A knife can be hidden behind one's pants. Toilet paper might just barely fit in a pocket."

"Oh, perhaps there may be some method of concealing the knife, but what about the toilet paper? Recall, the roll found in the men's toilet yesterday exceeded the thickness you could simply pocket."

"… Ah."

"That roll, although somewhat less than a brand new roll, wasn't small enough to fit into a pocket. Even if you tried forcing it in, it would bulge noticeably, making it hard to imagine the perpetrator making that choice."

"So, what do you propose?"

"Hence, the appearance of the bucket."

— The bucket.

"Ah, I see…"

Unintentionally, Yuzuno murmured aloud. It's so obvious, so trivial, yet was a revelatory moment.

What was in the bucket wasn't water.

"The knife and toilet paper could easily be placed in the bucket. Hiding these two things inside makes it possible to approach the victim — or conversely, the victim approach the perpetrator — without exposure. Act openly, aim openly."

"… I see. This might indeed be the most effective method for bringing in a weapon."

Her brother seemed to understand now, nodding deeply. The screen still occasionally faced Yuzuno, which seemed strange. She thought, I'm not the one speaking.

"Now, that would be the reason the perpetrator carried the bucket to the scene? ... No, wait. The bucket should serve a more significant purpose."

"That's right. The primary reason for bringing the bucket was to wet the scene — that is, to soak the passageway to make the dissolved toilet paper inconspicuous."

In other words, to eradicate evidence of the timed device, the bucket was indispensable as well.

"So hiding the weapon was just incidental."

"… Then why did you pay attention to such a small detail?"

"Are you asking why I'd bother solving such a tiny mystery? Because, even small things can indeed be clues."
"For example, the aforementioned situation can be used to infer why the mop was brought to the scene."

"Mop?"

The car's speed slowed down. The national road was congested on that Sunday, making it difficult to move smoothly. The highway sign hadn’t appeared yet. Risome, absent-mindedly gazing out at the lined-up small shops, continued speaking, "... If the hypothesis I mentioned earlier—that the bucket was used as a tool to hide the kitchen knife—is correct, then the murderer really went to great lengths to avoid arousing the victim's suspicion."

"Well, since it's a planned murder, anyone would do that, right?"

"Then try to imagine the murderer, who is about to kill, is carrying a cleaning bucket with a weapon and tools to set up a trap inside it. To avoid leaving fingerprints, he’s wearing rubber gloves and rubber boots, meeting the victim in this state. To an unsuspecting victim, what would his appearance look like?"

"..."

The brother fell completely silent this time. Yuzuno also began to ponder. The murderer approaching her, with rubber gloves, rubber boots, and a bucket labeled "for cleaning floors." For cleaning—

"... Looks like a janitor."

It was a very frank answer, but Risome smiled at Yuzuno. It was a long-missed, cold smile.

"Yes, usually that's how it would appear—Brother, you heard that? The murderer looked like a janitor."

"I got that. What's the problem... Ah!"

"Do you get it? If the murderer tried to disguise himself as a janitor, he was missing one crucial item. Just carrying a bucket is not enough to clean without a mop."

"I see! So, that's why he brought the mop along!"

The brother clapped his hands on the table, causing the image to shake slightly from the vibration.

"Gloves, boots, bucket, plus a mop. Gather all these things, and it truly looks like a janitor. Amamiya is busy with dolphin care and performances and has no involvement in shark tank work. With an excuse, anyone could immediately deceive him. In undermanned Marumi, substitutes cleaning the keeper work area is a common occurrence."

He had confirmed with the director yesterday about substituting cleaners. Yes, just after figuring out that a roll of toilet paper wouldn’t fit into a pocket. By then, he had already deduced this far based on clues. —No, wait. He seemed to have asked another question right after...

"Alright, now comes the main point."

"Huh? We’re not at the main point yet?"

"Everything so far was merely a prelude, like 'The Swordsman in Black.' Don't speak, just listen."

Ignoring Yuzuno's surprise, Risome began to delve into what he called the "main point."

"Why did the murderer bring out the mop? It was to disguise himself as a janitor. That's clear, right? But think again, why did he need to disguise himself as a janitor in the first place?"

"... Didn't you already say? He hid the weapon in the cleaning bucket."

"But why was a cleaning bucket a necessity?"

"...?"

"There are many buckets of the same size on the shelf in the keeper work area. Compared to those, the one used for cleaning stored in the locker was old, with a crack at the bottom. Why did he specifically choose this nearly broken one instead of another bucket?"

"This... indeed..."

"Picture again. Suppose the murderer used another bucket, not the cleaning one. Rubber gloves, rubber boots, and just a normal bucket. Meeting the victim in this state, what would it look like? What do you think, Miss Hakata?"

"Ah? What do I think..."

Although she was told to shut up and listen just now, now she's asked to respond. While Yuzuno complained internally, she got her brain working.

This time there was no label saying "for cleaning." In normal places, it might still look like a cleaning person, but if in that place—the aquarium’s keeper work area—this outfit—

"... Like a keeper," she answered uncertainly, "I think the director mentioned something like that yesterday."

"Great answer!"

Risome did not applaud but moved his phone closer to Yuzuno.

"Keepers usually use blue buckets, the same color as the ones on the shelf. Yesterday, Daitabashi and others also carried buckets. Wearing gloves and long boots while feeding and tidying the tank is extremely common. Moreover, substitute feeding and cleaning is usual in Marumi. However, of course, this only applies to keepers with professional knowledge."

The conclusion Risome reached gradually became clear. Yuzuno and her brother waited quietly for him to continue.

"Based on this, we hypothesize that the murderer is among the keepers. This person meticulously planned everything, considering the necessity of the bucket fully. Because he needed a bucket to conceal the weapon, and to use it for erasing clues left while setting the trap. After entering the keeper work area, he put on gloves and boots near the rack out of Machou's sight, then picked up a bucket."

There were two kinds of buckets. One same color as what they carried, placed on the shelf, and the other an older, dark-colored bucket from the locker meant for cleaning—

"If he chose the cleaning bucket, not having a mop would look odd. But the shelf bucket didn’t have this issue. It’s the same as what the keepers typically carry. They ask me to organize the shark tank, or to feed the blue-striped snappers downstairs. Excuses are easy to find... But the fact remains, the murderer chose the cleaning bucket deliberately, bringing the mop along. Why?"

"... Because he’s not someone who usually carries a bucket," the brother answered lostly.

"Yes. The murderer couldn’t find any other excuse for carrying a bucket besides floor cleaning. So it's speculated that the murderer is someone non-keeper, unable to enter the keeper work area unless cleaning—meaning the culprit is an office or part-time worker."

He succinctly concluded and paused his narrative.

"Impressive...!"

"Focus on the road while driving!"

"Oh, okay." Hatori, in the driver’s seat, was amazed but got a cold reply from Risome.

"Oh dear, you really are smart; narrowing down suspects just like that!"

Yuzuno and her brother deeply understood the young police officer's sentiment. Mop, bucket. With only these clues, the once vague image of a murderer was determined.

A dramatic deduction.

"Well, it’s just a high probability. I even considered several abnormal situations. For instance, the real culprit might be a keeper trying to frame a clerk, deliberately using a mop and cleaning bucket."

"Oh, really? So this deduction isn’t foolproof?… Then why tell me?"

Her brother lay over the computer, and it seemed anyone talking with Risome would feel extraordinarily fatigued.

"It’s indeed not foolproof, but it can serve as a pointer. Prior, I suspected keepers for different reasons. But using this point, the focus could shift away from keepers. Therefore, I asked my brother to investigate the locker room. If a problem arose, the mop and bucket deduction was wrong. If not, it’d be correct and further pinpoint suspects."

"I don't understand, explain clearly… No, Risome, can you turn the camera back to you?"

"Huh? Why?"

You don’t want to see your sister, do you? Yuzuno thought. Her brother, hearing her question, awkwardly avoided her gaze and said, "Oh, it’s not that. I mean, at my angle, just now it's been your leg, that..."

Yuzuno didn’t let him finish. She slammed Risome’s right hand with a table tennis smash (without the paddle) she practiced from her team, sending the phone sliding under the seat.

"Huh? Why did it suddenly go black? Is everything alright? Hey, hey!"

"Brother, go die. Please, die already..."

Yuzuno pressed her temples. Since yesterday, her brother had seemed especially annoying, and now it’s turned to anger.

Risome, rubbing his pale hand, said, "Th-this is the smartphone I just bought... How many things do you intend to destroy before you stop?"

"Shut it! Risome, you're guilty too. Don't randomly take weird shots!"

"It was just an accident, oh geez, where's the phone..."

"Ah! Don’t touch my leg!"

Because Risome was squatting at her feet, Yuzuno smashed down on his head this time. No, it was at most a slice.

"I didn’t touch it! Besides, it was you who knocked it off!"

"Then I’ll pick it up, and you stay put!"

"What are you doing? Seriously."

"Hehehe."

"Don’t laugh!"

"Sorry." 

Under the bark, Hatori shut his mouth again. Why did she wear a school uniform when leaving the school—Yuzuno regretted as she retrieved the phone by her feet. Fortunately, it hadn't broken, still in call, the idiot brother's face clearly showed on the screen—

"... Ah."

"Huh? How is it? Is it broken? You owe me repair costs!"

Yuzuno didn’t speak, tilting the screen awkwardly so Risome could also see. He was also frozen with a sound "ah." Conversely, a man's voice came from the other end of the call: "Should I criticize Hakata, or should I yell at you... Both are viable! What are you doing?"

Appearing next to the brother was his superior's stern face, and he was the one her brother worried about getting "killed" by. Maybe due to staying up all night, his hair was messy and he looked extremely tired, but his long eyes were still sharp, staring past the screen at the counterpart.

"Hello, Officer."

"Hello nothing. I ask, what are you doing here?"

"Video calling."

"Why, you and Hakata! Leisurely! Friendly video calling?!"

Taking off her brother's earphones, Sendou's angry roars filled with noise intermittently reached.

"Sen-Sendou Chief, it's not what it looks like. I'm listening to Risome's reasoning..."

"Reasoning? This guy’s work was yesterday’s toilet paper. That’s done. What reasoning now!"

"Speaking of toilet paper, officer, was the replaced toilet paper found?" Risome asked fearlessly.

Sendou laughed mockingly. "There’s no obligation to tell you these things."

"Yeah? Anyway, it’s unrelated now, whatever. Probably found in the office trash bins, right?"

"How do you know?!"

The hysterical shout was deafening.

"Using reasoning, reasoning. Oh yeah, where was I in my story? Too much disruption, I forgot."

"Hey, you can’t just continue freely. End this call..."

"Oh, I remember, I mentioned narrowing suspect areas down to one person."

Sendou’s hand was almost on the keyboard, but hearing this, he immediately stopped his actions. Beside him, the brother widened his eyes too.

"... Narrowing suspect areas down to one person?"

"Yes. Alternatively, I know who the murderer is."

"Risome, wait, it's the first time I hear you say that."

"Didn’t I just say? If the locker room checks out, we can completely lock-down the suspect."

"I, I'm not surprised!" Sendou's trembling mouth revealed his inner turmoil, but he used a mocking tone to say, "We too roughly know who the murderer is."

"If using found toilet paper as evidence, it’s likely incorrect. The key aspects are the mop and the bucket. With just these two, you can find the murderer."

Risome’s indifferent tone only irked Sendou further. He clenched his fists, gritted his teeth, and finally sighed in frustration, leaning towards the screen saying, "... Fine, I’ll listen. Why can you narrow the suspects? State your basis."

"Are you willing to listen? Alright, then..."

Risome suddenly adopted a peculiar action. He glanced outside the window, murmuring to himself in a voice inaudible to the call, "The timing is just right." He took the phone from Yuzuno’s hand and continued speaking to Sendou, "Okay, I’ll explain now."

His compliance surprised Yuzuno. She had been convinced that the seemingly dominant Risome would retort with something like "asking for help means showing some humility,” leading to another argument.

She immediately realized the reason.

"The murderer is likely among the clerks—this is the conclusion of my earlier deduction. For more details, ask your brother later. To summarize..."

At first, his narration flowed like a lecture. However, just as it was about to reach the core, an anomaly arose. The anomaly wasn’t in the lecture content but the communication method.

"To put it simply, this deduction is a pointer, and the vital aspect lies elsewhere."

"Hey, Risome... Risome... Hey, hey... bzz... bzz."

The picture became unclear, and the sound—no, from hearing, the noise grew louder. The police officers' faces turned into mosaics, the sound kept cutting out, barely audible.

This issue conveniently arose as the car lifted its speed on the highway.

"Oh, sorry, bad signal. Anyway, we’re on our way over, see you there. Goodbye." 

He nonchalantly bid farewell and disconnected the call. Then with a casual operation, he set the phone down on the seat. The screen displayed an "exit" icon.

—It was intentional all along. Yuzuno’s intuition told her.

"Did you know from the start that entering the expressway would cut the call?"

"This service is notorious for signal cut-off as soon as you enter expressways."

Stretching like a cat, Risome explained with a big yawn. Hearing his explanation, Yuzuno understood everything.

If it were a phone call, it would’ve had signals on the highway; this was proven yesterday. So he chose a network call, which gets weak on the highway, cleverly timing it—his initial lines were "easy does it," and just now, "the timing is just right"—he had planned, the call would naturally disconnect before addressing the core content. Naturally, he first extracted the police information he wanted from the other party.

From deciding to use communication with the police as an exchange condition, he had intended this.

"... You’re quite the strategist."

"What do you mean?"

He feigned ignorance like a child. Truly detestable.

"But, why only say half of it? Wouldn't it be better to finish?"

"If I say the murderer’s name, your brother might arrest them immediately. Without me at the scene, I miss the opportunity to talk with the murderer."

"Is the opportunity to talk that crucial?"

"That's most important. That’s my interest."

Being identical in speaking and frankly quite different, he wasn’t concerned about arresting but communicating with the murderer. What would he say?

"Moreover, although I claimed to lock the suspect, the evidence isn’t solid yet. More confirmations are needed past this."

"... But from your tone just now, you spoke as if it were absolutely certain."

"Just using that tone. Only."

He readily confessed he was lying. Yuzuno nearly wanted to bury her face into the seatback.

"... Seriously, don't even know how much truth... Wait!"

Suddenly noting how entering the expressway cut the call. If so, then the preceding call issues were also calculated? Sendou’s appearance perhaps was accidental, but before that...

"Risome, did you deliberately photo my leg for timing adjustments?"

"Well, that."
"He said this while trying hard to plaster a smile on his face. This time, there was a powerful strike, hitting the side of his abdomen.

'Why, why are you using violence...'

'This is self-defense against sexual harassment. If you have time to rack your brains over this, you'd better put effort into serious deduction!'

'No, my deduction is indeed serious... and it is true that the suspect has been narrowed down to one person.'

'...So who is it?'

Risome coughed a few times, adjusted his breathing, sat up straight in his seat, and said, 'As I mentioned earlier, the reasoning that the zookeeper is involved is just a pointer. There's actually a deduction related to the mop, which is the core of the issue, so I kept it hidden from your brother and others. Combining these points with the fact that nothing unusual was found in the locker room, there is currently only one suspect left.'

'Who is this person...?'

Yuzuno pursued relentlessly. Hatori, in the driver's seat, also perked up his ears. Risome's black eyes fixed on Yuzuno, and he announced the name, 'Veterinarian Mitsuhiko Midorikawa.'

2 "Resounding Sound"

The aquarium was still under lockdown. The square was empty, with only the fountain futilely spraying water. Several media vans were parked near the entrance, and reporters and cameramen were preparing for live broadcasts.

Risome maneuvered behind them to avoid being noticed, then unlocked a side gate and slipped inside—just as his brother had apparently taught him. 

He headed straight to the exhibit area. Having bypassed the entrance, he was immediately greeted by the large tanks. The lighting was somewhat dimmer than during opening hours. Yuzuno's face lit up, as if determined to sweep away yesterday's dismay.

'Wow, amazing...'

Hundreds of fish formed a panorama in front of Yuzuno's eyes. Perhaps it was psychological, but Yuzuno felt that without the spectators' gaze, these leisurely aquatic creatures appeared more relaxed than usual. Then Yuzuno realized: Is this place exclusively ours?

'I've left you here.'

'Hey, Risome, wait! We rarely get to come here, let's take a look!'

'We didn't come here to watch fish!'

'But it's such a rare opportunity... Wow, a ray! It's so big! Just like a shark!'

'They're inherently similar species, of course. Rays have gills on their bellies, while sharks have them on their sides.'

'Huh, that's how it is... really?'

'I don't know.'

Risome walked briskly ahead. Although Yuzuno was unwilling to leave the rays, she repeatedly called out, 'Wait,' catching up with Risome's pace. She seemed to have understood her brother's feelings from yesterday.

'Isn't it thrilling? The whole aquarium to ourselves?'

'If I let myself get excited, it would be a disaster. Weren't you here yesterday as well?'

'No, yesterday doesn't count... Ah, speaking of excitement, what's Kaori doing?'

'What kind of association is that? Kaori should be sleeping at home today. She said she was exhausted yesterday.'

It's natural for someone to be bedridden after witnessing a murder scene.

'Is she alright? Should we go visit her?'

'No need, she's tough. Don't worry... I'm really going to leave you here.'

The merciless Risome told Yuzuno, who had paused in front of the cylindrical tank for cherry bass.

'Can't I just look for a bit? Risome, don't you have a favorite fish?'

'No, I don't. If I had to choose, octopuses and squids are alright. And sea anemones.'

'Why are they all creatures with tentacles?'

The two chatted idly as they progressed through Building A. Yuzuno enjoyed the aquarium devoid of any visitors. She sighed alone in front of the coral reef tank and captivated by the red pinecone fish. In the special exhibition area, a spotted crab with a name similar to her own pronunciation caught her attention. Each time, Risome urged her to hurry along. Yuzuno felt she was similarly hurried when she came with her brother in the past.

As she approached the tank of scythes, intending to study its characteristic yellow and black striped fish with prominent foreheads, a gruff voice called out from an unexpected direction: 'Ah? Weren't you here yesterday... what are you doing?'

The glass tank was open, connected to nothing above, allowing staff to peek in from the back. Two people stood there, both wearing yellow Polo shirts, showing off their developed muscles. They were zookeeper Daitabashi and intern Oiso, who were gathered together in the meeting room last night.

'Here again today? I don't care if you're consultants or whatever, it's a lockdown. What are you doing here?'

'That's what I'd like to ask you, Mr. Daitabashi. It's commendable to be working under lockdown.'

'Of course, the entire staff is on duty. Whether it's a murder or a restricted area, human affairs don't concern the fish.'

Daitabashi lifted a bucket and leaned it against the tank, somberly spreading feed, a kind of minced mix. Dozens of scythes darted from the coral shadows, eagerly partaking. Oiso started feeding as well.

'Well, it's the perfect opportunity. I have something to ask Mr. Daitabashi. I might as well ask Mr. Oiso too,' Risome said, looking up at them.

They paused their work and asked, 'You have questions? Are you really playing detective, kid?'

'I already said I'm no detective. But what I want to ask is no big deal; I heard you fed the tank beside the shark tank yesterday. The time range was from 9:40 to almost ten. Is this something you do daily?'

'Yes, it has to be done at that time.'

'If things are the same as usual, after feeding, where do you go? Back to the zookeeper room?'

'No, I'd go directly to the new building's tank to add food.'

'I see. So you leave Building B... but yesterday, after feeding, you went to Dr. Midorikawa's office. Why?'

'Why? ...Dr. Midorikawa called me to his office yesterday to consult about the clownfish infection.'

'Dr. Midorikawa called you?'

Risome confirmed once more. Daitabashi nodded his rock-like chin and said, 'He didn't directly call but had Ayase relay the message to me. Even if he hadn't said anything, I would have planned to see him...'

'That part doesn't matter. Essentially, Dr. Midorikawa asked you to drop by the clinic. So, you did something different from usual. As a result, you established an alibi in the clinic. Is that correct?'

'How are you talking? Are you suspecting me?'

Daitabashi shouted, glaring fiercely at the short Risome.

'No, I'm not suspecting you. Not suspecting you... Then, Mr. Oiso.'

Risome calmly smiled and turned to Oiso, who had been silently feeding. The young man gave a brief response.

'I want to know about Mr. Amamiya, who was killed. You're close in age, what kind of person was he?'

This question was uncharacteristic of Risome. In previous detective work, he didn't proactively inquire about the victim's character.

Oiso hesitated: 'What kind of person, how should I put it...' Daitabashi interjected, 'An unreliable guy, shallow and flashy. Right, Oiso?'

'No, well... he was serious about his work.'

'He was good as a trainer, but whether he was passionate about the work is unknown... He often had an arrogant smile, enough that I wanted to punch him sometimes.'

Daitabashi appeared very displeased. According to Kaori, Amamiya was a handsome man, and it sounded like that made him unpleasant.

'Oh, his arrogant smile got eaten by the sharks, huh,' Risome quipped arrogantly, then asked Oiso again, 'What do you think? Was Mr. Amamiya unreliable?'

'...Well, sometimes I felt that way, but I'm not sure. I only joined six months ago.'

'Oh, so you're an intern?'

'You, you know a lot... Plus, I'm seriously rigid, so I didn’t quite fit with Mr. Amamiya, I can't judge.'

'Alright, now that I've cleared things up, get moving! Go on your date somewhere else!'

Daitabashi, talking while scattering the last of the food into the tank, triggered a denial from Yuzuno, only for him and Oiso to disappear into the backyard.

Risome and Yuzuno continued to explore deeper into the aquarium. Encountering a giant spider crab with daunting legs or playful jellyfish, they (mostly Yuzuno) paused every so often but eventually reached the side gate of Building B. Before entering, Yuzuno took a glance at the shark tank's glass. All lights were off, a large sign reading 'Under Adjustment' hung on a backdrop of pitch-black.

Passing to the back area, they happened upon Shibaura emerging from a storage room. Seeing two unknown individuals startled him, deepening his forehead wrinkles. Risome made no greeting, simply walked past, turning left at the corner. Ahead lay a door marked 'Food Preparation Room,' which he ignored outright.

Risome hurried towards his destination—'Clinic' marked the door ahead. 

—Veterinarian Mitsuhiko Midorikawa. The single, crucial suspect among eleven people.

He might be the culprit. Now, on the opposite side of this door, Risome was about to unveil the mystery of the case.

Yuzuno, right behind him, grew increasingly tense, just as she had before yesterday's match.

Fortunately, the door was unlocked. Knocking, they pushed it open, finding only Midorikawa inside. Seeing Yuzuno and Risome, he simply said 'Oh,' with seemingly little surprise.

'You're from yesterday... need something from me?'

'Yes, I have something to discuss. It's very important, regarding the case...' Risome entered the room, surveyed its roughly six-tatami size, then said, 'This, this can't be helped...'

Before Risome finished speaking, he leaned dejectedly against the wall, leaving Yuzuno puzzled.

'Huh? Huh? Risome, what's wrong?'

'This can't be helped.'

'What can't be helped? Your life and hobbies?'

'This can't be helped... not that. This can't be helped.'

'You're reciting poetry or something? What's wrong, Risome? Risome!'

'Are you injured?' Yuzuno shook Risome's shoulders, and from behind, the doctor stood to say, 'Sorry, if that's the case, I'm generally only a vet...'

Midori turned to the visible room and added, 'There's no medical supplies here either.'

Upon entering the clinic, there was a small desk and beyond it shelves filled with neatly organized files. Nothing else was there, only a single file, clipboard, and pen holder on the desk. This was a simple room with no need for organization. Looking at the shelves, each file's spine was labeled with periods and animal names, such as '98 False Killer Whale.'

In that case, instead of calling it a clinic, it should be said, 'This room is used for record keeping. I was reviewing tropical fish records. Should I take you to the clinic in the new building?'

'A clinic... there's one in the new building too?'

'Yes, there are medical tools there. Though they aren't for treating humans, minor injuries can be handled.'

'Oh, I see. As expected, with aquatic life as the subject, corresponding facilities would be necessary. Given a new building, it's unlikely this old structure would have a functioning clinic, right? A record room... Yeah, during the incident, you said you were “revisiting old records,” even telling Daitabashi “to come to the downstairs clinic.” It makes sense now. I understand, I get it.'

Risome nodded painfully.

'I still don’t get what's happening, so was it the room that dashed your expectations?'

'Yes, my expectations were dashed... I thought this was your usual clinic, filled not only with medical instruments but also various personal items, like a navy blue Polo shirt.'

'Personal items? Polo shirt? Those are oddly specific conditions. Apart from the T-shirt I'm wearing, I don't have any others.'

Midori tugged at his garment, a T-shirt as light green as his name today.

'Logically considering, that should be it... Has this room always been a record room? It didn't suddenly change yesterday?'

'Of course. It's been a record room since the new building was completed. Anyone you ask will say the same.'

'Really? Then, ultimately... ultimately...'

Under Midori and Yuzuno's focused gazes, Risome fell silent. Then he shouted 'Ah' loudly, telling Midori, 'Sorry for troubling you.'

He bowed slightly, turned away seriously, and Yuzuno, bewildered, strove to catch up with him.

Facing such a Risome, Midori remained indifferent and replied, 'It's alright.' Most likely losing interest in Risome, his voice was extremely cold.

Heading into the corridor, Risome proceeded toward the transport entrance at the end.

'I say, Midori isn't the culprit, then...'

'No, I made a mistake. I acted too foolishly.'

Around the corner, there was another staircase. It didn’t lead underground but merely to the second floor.

'I haven't considered the matter of gloves properly. Damn it, I should have confirmed this yesterday. This is the worst-case scenario; all efforts so far have been wasted. Back to square one...'

Risome lamented endlessly as he climbed the stairs, as if mumbling a dream. It seemed he realized a significant error upon inspecting the clinic.

'Back to square one, meaning there are still eleven suspects?'

'Exactly.'

'Still no clues?'

'None, I'm throwing in the towel.'

At the stairway to the second floor, Risome truly raised his hands, though it was a joke, with a somber expression. Yesterday, on the same corridor, his confidence was unshaken.

'I was always just lucky; the approach was wrong. Ah, finished, finished, I'm done. Lately, it's all been troublesome matters: wrong deductions, broken air conditioning...'

'Bringing up old issues at a time like this... Anyway, keep it together.'

Yuzuno earnestly supported Risome's arm, preventing him from becoming one with the wall.

'Not every part is wrong, though. You got the toilet paper trick right.'

'That's correct, though it didn’t lead to finding the culprit... No, since it's like this, I guess I still need to rely on it...'

'That's right, do your best! Risome, hang in there!'

She wholeheartedly echoed the encouragement from her captain yesterday for Risome. Risome and Yuzuno’s reactions were exactly the same: 'No matter how much you cheer, it's futile...'

Just then, a voice emerged from behind them: 'Oh my, clinging to each other’s arms, how lovely.'

A long-haired, hunchbacked man—Jin, headed into the document room.

3 Sickly Dolphin Girl

The document room was a barren room, with only bookshelves for files and a few cardboard boxes, resembling the clinic downstairs—no, reversed, perhaps the clinic downstairs merely resembled this document room. Without windows, strong sunlight only filtered through the exhaust fan's slits deep within the room. Jin stood by the exhaust fan wall, watching Risome and Yuzuno with great interest.

'If you're on a date, it's better to go admire the tanks than stay here.'

'I told you, it's not a date.'

As Yuzuno denied, Jin chuckled, 'Alright, alright,' and asked Risome, 'What do you need from me?'

'Something I need you to confirm.'

'About the case? That's fine, but please make it quick. I'm on break right now.'

Only nominally, as Kaori pointed out, he enjoys slacking off during work.

'Are you taking a smoke break?'

Suddenly, Risome said. Jin, hearing this, immediately widened his usually squinted eyes: '...Oh, indeed a detective, huh? How did you know?'

'Because the newspaper club members said you gave them candy.'"
I think you might be craving a smoke. Also, since you have a habit of zoning out occasionally, and this room as a resting place also has an exhaust fan, I guessed that you might be hiding here to smoke.”

“I need to keep up with the times—the whole aquarium is non-smoking, which makes things difficult for me.”

He took out a pack of cigarettes and a few candies from his pocket and gave the candies to the two of them. They were small packaged hard candies with riddles printed on the back, grape-flavored, very childish.

“What do you need to confirm?”

“I’ve already confirmed it, so I'll be leaving.”

“Wait, wait a minute.”

Even though it was Tsutou himself who urged Risome to hurry up, he now hurriedly stopped him.

“You’re too fast, without even a question. Let’s talk a bit; I’m interested in solving the case, actually.”

“But you’re also a suspect, aren't you?”

“That’s why I want to solve it. I quietly asked the director yesterday how you broke the alibi trick. Wow, it was toilet paper, so interesting. But, if I observe the scene carefully again, I believe I can also solve the mystery.”

“What kind of person do you think the culprit is?”

Tsutou took a cigarette, lit it with a lighter.

“Well… It’s obvious that he's quite irrational. If it were me, I definitely wouldn’t kill someone in such a place.”

He exhaled a puff of white smoke and gestured with his arms to encompass the whole Building B.

“There are cameras at the entrance, and staff walking back and forth outside. While you can determine the time slots when no one entered the tank through the duty roster, it doesn’t mean it’s 100% safe. Yet the killer killed Amamiya, which means—”

“Which means?”

“They harbored a strong animosity towards Amamiya. Cutting his neck and feeding him to the sharks, they wouldn’t be satisfied without some form of insult. The murderer is meticulous, bold, with strong animosity and madness. This is why I find the toilet paper trick interesting. Despite the cleverly set trap, the method is quite childish.”

“Is Mr. Amamiya someone who could evoke such strong animosity in others? Was there any conflict among the staff? Like romantic entanglements.”

“I’m not sure about that. Although he often approaches women, it’s more like he’s teasing them rather than truly wooing them. So, I don’t think he would cause much hatred in this regard. I suspect it’s a work-related issue.”

“But I heard he was very diligent in his work.”

“About two or three months ago, the zookeepers proposed to add another dolphin. Funami and the director, who are in charge of administrative tasks, said there weren't enough resources and rejected the idea. At that time, Amamiya had an argument with them. However, I hid in my own castle, so I’m not very clear about the details.”

“Is the document room your castle? What a worthless lord you are.”

Yuzuno thought to herself, aren’t you also the lord of the activity room, talking like that about others.

“Your information is very valuable; thank you very much.”

Risome gave a bow to the smoking king of slacking, exhaling clouds of cigarette smoke. 

Just as they were about to leave the room, Tsutou suddenly seemed to remember something, saying, “Speaking of Funami, he made some odd moves yesterday after you left.”

“Yes, I guessed as much.”

Risome nodded knowingly, seemingly fully aware of the situation, and left the smoker’s castle.

There were four people in the office.

Today, Mizuhara was still casually wearing a T-shirt, sitting by the table facing the computer. Funami was going through the files in front of a bookshelf. A part-time university student, Honoka Nishikawa, who looked about Yuzuno’s age, was operating the copy machine. Next to her was the resting deputy director, Yuko Ayase, holding a steaming paper cup in one hand.

“Oh my, aren’t you the detective student from yesterday and their little assistant? Is this a date?”

Repeatedly, the same question was thrown out just as they entered, just like what Daitabashi and Tsutou had said. Yuzuno insisted loudly, “I said it’s not.” But it was uncertain whether they really took in her words.

Risome, however, silently observed the interior of the room, his dark eyes darting around from left to right. He scratched his chin and gradually spoke up:

“I have something to ask everyone.”

“What is it?”

“About Amamiya. I’d like to hear from everyone about what kind of person he was.”

“What kind of person… Hmm, a weirdo, maybe.”

Not sure whether it was her quick temperament or her usual impression, Mizuhara immediately responded without the hesitance that Oiso had.

“However, this isn’t to say he was eccentric; it’s just that among the zookeepers, he was quite a unique type. He didn’t show affection towards animals.”

“No affection?”

“I mean, he just completed his tasks without wanting to get too involved. Tomoka often lamented that there was something hard to understand about him.”

“Please stop. It feels like saying bad things about someone who passed away... Didn't Mr. Amamiya do well in both feeding and training?"

Ayase slightly reproached. The evaluations of Amamiya by these people were consistent with what Daitabashi had said. He was competent but had a condescending attitude.

“I heard he was quite flirtatious; what do the female staff think?”

“Yes, yes. Miss Ayase is around his age, so he often tried to get close.”

“He didn’t exactly get close, just jokingly asked me if I wanted to have a meal together.”

“Oh, he asked me a while back too… But I declined,” Nishikawa raised her hand timidly.

Mizuhara leaned back exaggeratedly and said, “Even Honoka wasn’t spared? This guy really doesn’t discriminate.”

“Miss Mizuhara, didn’t I ask you not to speak like that?”

“Oh, sorry, sorry… But I think Mr. Amamiya’s true goddess was still Tomoka.”

“Tomoka… is that Tomoka Takino?”

“Yes, yes. They both were in charge of the dolphins; I saw them getting along well in this aspect. Isn’t that right, Mr. Funami?”

“Huh?”

Mizuhara turned her head to look at Funami by the bookshelf. His back trembled, and he said, “What? Are you talking about Mr. Amamiya? Yes, he seemed to get along well with Miss Takino, very well. Hmm.”

Fast-talking and rambling. Indeed, just as Tsutou had said, he was acting suspiciously. Risome whispered to Yuzuno, in a voice only she could hear: “This guy is really easy to read.”

However, something strange happened.

“But could we really tell if Mr. Amamiya was sincere in his actions? When he invited Miss Ayase, it seemed like he was joking.”

Funami redirected the topic towards Ayase as if trying to shift everyone’s focus away from himself quickly, and Ayase, like Funami, raised her volume and said: “Huh?… Oh, right, yes.”

Before this, her answers were quite natural, and now she was just repeating what she had already said.

Yuzuno tilted her head, unable to understand what was going on with her. Risome also seemed puzzled by this. He squinted at Ayase, who noticed and awkwardly lowered her head, staring at the paper cup in her hand—

At that moment, the door behind Yuzuno and them was pulled open.

“I’m back… Nice, nice, the police finally agreed.”

The worn-out shark keeper Fukamori, with a buzz cut that left a lasting impression, walked into the room. Ayase lifted her head, and immediately steered the conversation towards him: “Really? That’s great. So we can clean the tank.”

“Yeah, I’ll take a short break and then start. Drain the water, and clean the underground filters too. Also, the floor of the overhead passageway… Oh, the items in the cleaning supply cabinet were all taken away, right? Such a hassle. Forget about the buckets, but those mops were brand new, just bought last month.”

Fukamori complained to himself while operating the coffee machine, and then he finally noticed the two unrelated people present. “Oh? You’re the ones who came yesterday… What are you doing here? An aquarium date?”

“No, no.”

“Don’t worry, we’re leaving soon.”

Risome seemed to have gotten used to Yuzuno’s denial, adding a line too. Then he turned to the two leaning against the wall and said, “Mr. Funami and Miss Ayase, could I have a word with you?”

The accountant and deputy director exchanged a glance, bewildered, as they followed Yuzuno and them out into the corridor.

Once Risome closed the door, he crossed his arms and confronted the two people he called out. A slight layer of sweat emerged on Funami’s forehead, and Ayase turned her head to the side, avoiding Risome’s gaze.

Even to Yuzuno, these two were obviously acting strangely.

“I say… what do you need us for?”

“Miss Ayase, when you were in the director’s office yesterday, you saw something through the window, didn't you? Like someone passing by in the corridor.”

“Yes, I did. I also told the detectives yesterday, that I saw Tsutou returning from the document room…”

“Did you see anything before that?”

Risome’s direct question rendered her speechless: “How did you know…”

“You saw, right? I knew it… Mr. Funami, please don’t turn away.”

Funami, who was pulling back little by little, froze at these words. At the same time, Yuzuno felt Risome poking at her back, which she interpreted as a signal to grab him. So Yuzuno slipped in from the side and held tightly onto the sleeve of Funami’s T-shirt.

“Well, Miss Ayase, you didn't tell the police about this, did you?”

“No, no. I just glanced briefly and couldn’t be sure I actually saw anything, so…”

“No worries, that part doesn't matter. I’m not a detective or the police. So, please tell me what you saw.”

The authority of the young deputy director was completely gone from Ayase’s expression. She adjusted her glasses, askew from embarrassment, and whispered, “Just a moment before seeing Tsutou, I saw, I saw Funami suddenly run past my field of view and immediately return to the office…”

Yuzuno sensed a faint force pulling the sleeve she was holding. Thinking she should not let him get away, she tightened her grip. Needless to say, this problematic person staggered two steps forward and had no choice but to stand before Risome.

“Mr. Funami, Miss Ayase said so. It’s strange, isn’t it? Didn’t you say you were in the office the whole time?”

“No, no, no. It's different from what you think; there was a reason for that.”

“Then tell me.”

“…I, I spilled the coffee. Some of it got onto the files I got from Izumi.”

He confessed in a nearly inaudible voice.

“So I hurried to clean it up, but there were neither towels nor cloths in the room, and unfortunately, the tissues were also used up. So I quickly ran to the restroom to grab some toilet paper. That's it, that’s all there was to it. I have nothing to do with the case at all… Really!”

Despite the heightened intensity in his words, Risome remained nonchalant: “So you went to the restroom? The men's restroom?”

“Right, yes.”

“Why didn’t you tell the police? When I asked yesterday, you didn’t mention it either.”

“I thought it wasn’t worth mentioning, so I didn’t tell the police… When you started questioning, I just learned that the alibi lost its meaning and that the restroom was very important. Hence, I thought if I admitted it then, I’d surely be suspected.”

“That’s why you couldn’t say it. Huh?”

“Please, believe me! I still have the files with coffee stains, and the roll cores from the toilet paper should be in the trash too!”

Funami clutched Risome’s shoulders, his eyebrows distorted with pleading. Hearing him mention the trash can and the roll cores reminded Yuzuno of the video call in the moving car and the conversation between Risome and Sendou.

He speculated about the location where the toilet paper core was found: “I guess it was in the office trash can.” At that time, he had already figured out the location.

During the incident, only Funami remained in the office the entire time. And now, he admitted it himself, that he took the toilet paper.

“Where was it?… I just took one from the holder in the stall as usual.”

“Do you remember the time you went to the restroom?”

“A-around exactly ten o'clock, maybe. When I spilled the coffee, some got on the watch as well. I was worried, so I looked carefully. At the time, it was one minute till ten. So, I estimate that was the time.”

“Is the watch accurate?”

“Of course. All staff were issued the same radio-controlled clock, so it’s precise. Look, Miss Ayase also has one, right?”

Indeed, both Funami and Ayase wore watches with yellow bands on their wrists. Yesterday, Kaori also mentioned that other staff wore the same type of watch.

“The watch didn’t break. Given it’s waterproof, it naturally wouldn’t be damaged by coffee. The director has a weird thing for being stingy at peculiar places; it’s annoying. Ha ha ha… ha…”

Though he laughed it off, the atmosphere in the corridor remained chillingly cold for a summer’s day.

“Mr. Funami, I have one last question. When you went to the restroom, was there anything unusual around?”

“Uh… nothing, didn’t notice anything. I went in and out quickly.”

“I see. Thank you!”

Risome unilaterally ended the questioning, leaving Funami and Ayase to themselves, and headed towards the zookeeper room. Funami, perhaps still feeling suspected, shouted once more, “It wasn’t me! I really didn’t do it, and I’ll immediately inform the police of the truth. Can you believe me?”

“…I’d love to believe you.”

The last line Funami received from Risome was a phrase tossed back at him:

“I don’t have any evidence to suggest you’re not the culprit.”

“You knew from the start that the toilet paper roll core was thrown into the office trash can, right?”

“The toilet paper that was supposed to be on the hook was not in the restroom. If it wasn’t there, it must have been taken.”

Back on the first floor, Risome leaned against the wall of the feed preparation room immediately. Just as his motto goes, “talk to at most three people a day,” he seemed very fatigued; he shook his head and rubbed his shoulders as he explained, “Whoever took the toilet paper, whether the culprit or someone else, needed a good reason. The most natural reason would be that they spilled something and needed to wipe it up. This paper is made for cleaning things, after all… I mean, it can also wipe drinks.”

Speaking this, he seemed embarrassed even himself.

“In that case, who in this building could have spilled a drink and had no choice but to go to the restroom for toilet paper to clean it up? First, we should eliminate the zookeepers and part-timer Nishikawa. Because their towels should be close at hand. So, that leaves Midorikawa from the 'Vibrant Sound', clerk Tsutou, and Funami.”

“Midorikawa isn't 'Vibrant Sound,' he’s the veterinarian… What about Ayase and Mizuhara? Aren’t they clerks too?”

“How would women enter the men’s restroom?”

“Oh, I see…”

But yesterday, he said: just because someone entered the men's restroom doesn’t necessarily mean they’re a man—

No, that’s not right either. This time, he assumed taking the toilet paper required a “solid reason.” Suppose Ayase was the culprit and took the replaced toilet paper back to her room; what explanation would she give if discovered?

Saying “I wanted to clean up a spilled drink” clearly doesn’t justify entering the men’s restroom as a woman.

“Well, first about Tsutou, there’s no water in his slack-off document room. Regarding Midorikawa, towels or napkins should surely be in the infirmary, so he’s ruled out too. That leaves Funami. I assumed the toilet paper roll core was in this guy’s office.”

“No towels or napkins in the infirmary either.”

“So I was purely lucky in my assumption during the conversation with the detectives.”

What he muttered to himself earlier, “Lucky indeed,” referred to this. 

“Though the infirmary incident overturned the inference, Sendou’s straightforward reaction made me certain the roll core was in the office trash can. So, I first went to the document room and, after confirming there was no water inside, slipped into the office.”
"In the neatly organized office, indeed, no towels or anything of the sort were found. Moreover, Funami, who was present, was clearly hiding something.

'So, you started questioning him?'

'Yeah, but I didn't expect Ayase to fall for it too.'

Ayase was visibly shaken when Funami spoke to her. Perhaps it was because she witnessed the moment when Funami went to the washroom, and Funami concealed this fact, leading to her vigilance.

'Hmm, I see...' As expected of Risome. Although he was only half right, this reasoning was truly brilliant. Yuzuno savored his words, nodded, and continued, '...So, what if Funami took the toilet paper?'

'Nothing special.'

Risome once again put on a helpless look. 'The mystery of where the original toilet paper on the holder went is solved. It has nothing to do with the case; Funami took it to wipe up coffee... However, since there's no evidence proving he isn't the culprit, his testimony is utterly unreliable.' Among the eleven suspects, Funami is also notably listed.

'At ten o'clock, Funami indeed went to the washroom, and Ayase saw him. But, one might think Funami is the culprit, deliberately acting this way to handle the replaced toilet paper.'

'But... But Risome, didn't you say yesterday? If it's about disposing of toilet paper, the washroom is the place with the least suspicion.'

'That's precisely why he acted like that. A typical culprit wouldn't specially take something that could be left there back to their own room. Precisely because one wouldn't normally do so, they wouldn't be suspected. Maybe that's the clever plan he had in mind.'

'If you start thinking that way, it never ends!'

'Exactly,' Risome agreed deeply, then weakly pressed the back of his head against the wall. 'In short, that guy's testimony is of no use at the current time. Being wrong about the infirmary reasoning is really discouraging...'

'Is someone there?' Suddenly, the door beside them opened. Holding an apron in one hand, and a light blue bucket in the other, the zoo manager Izumi's plump figure appeared.

'Oh my, isn't it the two from yesterday? A date in a place like this?'

'No... How many more times do I have to say this?' Yuzuno sighed half in frustration, immediately swallowing the other half.

'Ri, Risome... Look, Risome...'

'Huh? What is it... Oh, blood! Miss Izumi, there's blood on your apron! Is it Mr. Amamiya's?'

'You're too direct!'

'Huh? This? Of course not. Smell it.'

Izumi nonchalantly lifted the apron. Yuzuno leaned closer and smelled a fishy scent.

'...Fish blood?'

'Yes, yesterday the police made the same mistake. This is a place that keeps living creatures, so naturally it's the blood of these creatures.'

Izumi laughed heartily. It's no wonder Kaori calls her 'Bold Mom'; indeed her voice is loud, as if she fears nothing in the world. Through a gap in the door, looking inside, the room was arranged like a kitchen, with water pipes everywhere, aprons folded, cutting boards, styrofoam containers filled with fish, buckets, and towels, etc.

Izumi went back inside, put away the apron and bucket, then came out and said, 'It's rare that today is Sunday, with no one else around. How nice it would be for you to enjoy the exhibition area... I'm off to a particularly suitable place next.'

'I said it's not a date... what place is particularly suitable?' 

'The dolphin pool in the new building...'

'We are indeed on a date, thinking it over, yes, it's a date!'

At the mention of a long-anticipated word from a few days ago, Yuzuno dashed over without a hint of shyness. Risome was beside her, twisting his face: 'When did it become a date?'

The new building is a gigantic hall with a gently curved passageway. It's an open structure without a designated tour order, allowing free movement between different water tanks. In the center is a wide tropical fish tank, with colorful fish and coral recreating the southern sea’s visage. At one end of the hall, there is a large resin tank facing the shark tank, where the display sign also reads 'Under adjustment,' and the creatures are not visible.

Inside the hall, there are tiered seating areas surrounded by a performance pool. The rear of the pool opens to the outside, offering an expansive view of Yokohama's sea. Possibly there is a yacht marina nearby, with several yachts slowly cutting through the waves.

Izumi was headed to the back of the performance pool, separated by walls and thus not visible from the audience seats. It was a waiting pool. Accompanied by the sharp sound of a dog whistle, two dolphins were swimming in the pool.

A black dolphin leaped high near the inside. Every time it reached the end and returned, Takino would throw fish at it from the bucket. Its fins struck the water powerfully, eye corners slightly white, resembling an orca from a distance.

Closer to them was another dolphin, calm compared to the black one, and smaller in size. Its body was white, with smooth skin glistening beautifully in the sunlight. Its partner was seasoned trainer Shibaura. Occasionally, the dolphin popped its head out, inviting Shibaura to pet its body with an affectionate air.

Black and white. Powerful and gentle. Both were joyously frolicking at will. The prominent snouts were irresistibly adorable, more than anything else—

'Cute, cute, cute...'

The exhaustion from club activities and competitions in the early summer vanished instantly. Delighted by the idols of Marumi, Yuzuno was filled with joy. Risome shielded his forehead with his hand, grumbling gloomily, 'It's so hot...' but Yuzuno paid him no heed.

'It looks lively,'

Izumi approached Shibaura and said. 

'Seems better than usual. Maybe it feels relieved knowing it can return to the tank... What are those two doing? I saw them at Building B earlier,'

'Allegedly on a date.'

'Huh? I heard they were detectives, thought they must be investigating.'

Exactly right. Mesmerized by the dolphins, Yuzuno currently couldn't care less about investigating.

'Is that Luffy?'

'Yes, indeed. Luffy, come say hello to the young lady.'

Beep beep—the dog whistle sounded sharply. But the white dolphin didn't react, leisurely swimming on.

'Oh dear... It still only listens to Takino.'

Shibaura scratched his bald head, Izumi chuckled along.

'In any case, it will be quite some time before it performs.'

'Ah... It's not performing? Isn’t it training?'

'It's in training. One of our idols was taken by the police, so we have to let it fill in.'

An idol of the exhibition area. Refers to the lemon shark?

'It's unfortunate. But, for Luffy, it's better not to perform. It has a gentle nature, and performing is too taxing for it.' 

Shibaura watched Luffy swimming with care, speaking slowly in unison with its movements, word by word. 

'It's a six-year-old female dolphin, born with poor stamina. Its skin is also very delicate, with transparent blood vessels when it was young, making it appear soft and pink.'

'Oh, that's why it’s named Luffy.'

Risome, who had unknowingly approached the water's edge, interjected. The old man beamed and said, 'Ah, you know it.'

'Of course, it's a work beloved by the nation.'

'You remember it well. Then do you know that dolphin's name?'

'Luca?'

'Not that old. Its eye corners resembling an orca is a feature of it.'

'Oh, then it's Tico.'

'As expected of a detective!'

I wish you'd stop using your insight in such trivial places.

'Tico and Luffy were both named by Mr. Shibaura,'

said Izumi. Tico was a wild-born dolphin from the North Sea, while Luffy was born in this aquarium.

'This child's mother is dead, its mother came from a Chiba aquarium. Starting from its grandfather's generation, it's been growing in a captive environment, so this child is the fourth generation in captivity. Recently, the fifth generation was born in Enoshima, causing a stir, but the fourth generation is already quite rare.'

'Born here, named by you, so you witnessed its birth? Were you previously training dolphins?'

'Rather than training, I was dedicated to being its keeper. Before Takino came three years ago, there was only Amamiya doing it all alone, so I came to help... Well, now that it's only Takino again, I've been reassigned here...'

'Talking about the past?' 

Just when the situation became awkward, Takino came over with Tico. Shibaura stalled, 'Oh, we were just talking about Luffy...'

But Risome probed deeper, 'Ms. Takino, could I ask about Mr. Amamiya? I’ve heard he's somewhat unyielding when it comes to work.'

'Sometimes he is indeed that way.' 

The one who nodded was not Takino but Izumi.

'He said that by taking on a business approach, it would also be more relaxing for the dolphins. How to put it, he always steps back, keeping a detached view when taking care of the dolphins.'

'It's a needed view, a virtue of Amamiya's,' Shibaura said and smiled at the other keeper, 'Especially you, Takino, putting in so much passion.'

'...Sorry.' Takino's voice was hoarse as she apologized. 

Risome continued asking, 'Ms. Takino, is it true that Mr. Amamiya tried to get close to you?'

'Not exactly getting close... he was just playing pranks on me, teasing his junior. Often making silly jokes to scare me.'

'Was it sexual harassment?'

'No, it wasn’t anything like that. Just those disturbances, like suddenly giving me a scare... By the way, I couldn’t find my dog whistle yesterday, I suspect Mr. Amamiya took it. If it were discovered, I’d be in grave suspicion...'

After finishing her displeased words, Takino withdrew her lips as if relieved. Tico was breathing beside her, white water flowers surfacing from the blowhole on its head.

'So, you weren’t in a romantic relationship?'

'Certainly not,' she replied strongly. It seemed like a sibling-like relationship, with the elder brother teasing his younger sister, rather than lovers. However, Takino's blushing didn't escape Yuzuno's eyes—perhaps she actually liked Amamiya.

Takino apparently didn't notice Yuzuno's suspicion when she smiled at Yuzuno and said, 'Didn't you mention wanting to greet Luffy just now? Can you squat here?'

'...Ah?' 

The specified spot was right by the water. Yuzuno, careful not to fall in, crouched down following her instructions.

'Luffy!' Takino called, blowing the dog whistle.

The white dolphin dove into the water, gliding along its own pace, circled the pool once, came before Yuzuno, and popped its head from the water surface. Yuzuno met its eyes. Big, soft eyes.

With a shrill screech, Luffy planted a kiss on Yuzuno's cheek.

'Oh...'

Then it swallowed the treat from the trainer, moved on finishing its task, and began to swirl around again, leaving Yuzuno feeling that chilly sensation on her skin.

Cute, cute, 'So cute...'

Yuzuno crouched moved by the lovely sight. 

'What's the big deal?'

Risome stood beside her in sharp contrast. 

'Detective classmate, do you hate dolphins?'

'It's just that, having my boyfriend's first kiss stolen, how could I not be upset?'

'I'm neither a detective classmate nor a boyfriend, I don't like dolphins. In the past, I almost sold a painting on some street in Tokyo.'

'Painting...? I don’t understand what you’re saying, anyway, I like dolphins.' 

Shibaura gazed at the two dolphins in the pool.

'Smart, doesn’t lie... such a great partner is hard to come by.'

'Yes, indeed!' 

Takino strongly agreed, clearly a devoted keeper. 'That's hard to say,' Risome concluded coldly, 'I don't really trust it...'

'It's you who’s untrustworthy,' 

a sturdy hand suddenly seized his head, visibly gripping harder and harder. His arrogant tone abruptly turned into a whimper, 'It hurts!'

After a day—or if counting the online talk, perhaps two hours had passed—Sendou and the elder brother appeared by the pool. Mizuhara stood behind them, holding a drawing board.

'What are you doing? Detective! Brain damage, what if it makes you dumb?'

'You're dumb enough as is. You hung up halfway through talking!'

'That was an accident, an accident!... But the result was not bad, my theory was totally wrong.'

'What? You are doing this again… Come closer.' 

Perhaps being conscious of the gazes from surrounding staff, Sendou led Risome to one end of the pool. Yuzuno, having barely shaken off the dolphin’s excitement, hurriedly caught up with them. Yusaku leisurely said, 'I saw that kiss earlier.' At this, Yuzuno combined the phone complaint's grievance and dealt a hard punch to his side.

'What’s wrong? Haven't you figured out who the culprit is?'

'Upon arriving here for final confirmation, I found my theory had strayed too far away, I’m sorry, please forget what I said this morning.'

'Damn! Today's just not going well!'

'You encountered something too?'

'at Building B, there were two staffers running over, crying...'

'Oh, that must be Mr. Funami and Ms. Ayase. Did they speak the truth? It's because I just interrogated them.'

'... Although I'm not fond of animals, talking with you makes me want to find a dolphin to console myself.' 

Dolphins and Risome, polar opposites.

'Well, that's not so bad. Although the testimony is still untrustworthy, at least the mystery of the toilet paper is solved... Speaking of toilet paper, brother, any findings on the roll used by the culprit?'

'Hmm... Oh. It's said the brand name is Joyce Paper's 'Ulysses,' supposedly it's sold in bulk stores around the Kanto area.'

'About the knife?'

'You mean the knife used as a murder weapon? That too is unclear where it came from, can't be a key clue.'

'Hey, Hakata, Stop broadcasting the information... why are you holding your stomach?'

'Huh? Oh, no special reason.'

The three conversed indistinctly under the summer sun and the clear water sounds. Yuzuno looked once more at the pool. Tico and Luffy occasionally stirred the water before them, Izumi and others gathered around the drawing board Mizuhara brought.

—That was a photo of Amamiya during a performance.

He was riding on Tico’s broad back, gliding over the water. The black diving suit and dolphin's skin color blended harmoniously, his slender yet muscular body was quite beautiful. Yesterday Kaori said he had 'Shibaura's leanness and Oiso's muscular build,' indeed it was true. He raised his left arm adorned with a yellow watch high, smiling at the audience with a childlike innocence.

'This was made in a hurry, does it look alright to you guys?'

'Yes, it's fantastic! Where would it be best to display it?'

'As prominently in front of the performance pool as possible... Ah, but if the audience focuses too much on the photo, that wouldn’t be ideal?'

'But at times like this, it should be noticeable. As long as Mr. Amamiya is happy... Plus, Tico and Luffy must be able to see it too.'

The four conversed in heartfelt affection.

An unreliable guy. A nonconforming personality. Ruthless at work. Favoring jokes, being a prankster. Skilled, having unique insight, and that smile in the photo."
Yuzuno felt that she finally understood everyone's opinion of Amamiya and painted an image of him in her mind. —A man impossible to hate.

However, he was hated by someone in the aquarium and was killed. This person, driven by the "mad" and absolute killing intent that appeared in Sendou's mouth, pushed him into the shark tank. This person was among them, among those who still worked with creatures today.

Who exactly was it? The range of suspects remained wide.

"…So, the frequency of the leak at the opening is indeed one drop every five seconds, right?"

"Yeah, that's the average."

"You see, I didn't break my promise. I've already given you another piece of information. You should go back quickly."

Before long, Sendou began to shoo Risome away again. Risome shrugged, waved to Izumi and the others, and left the pool. Although Yuzuno was reluctant to leave the dolphins, she followed him. He only said one sentence, "It's lunchtime."

"Yeah, I'm hungry. Let's find a place to eat… Oh, let's have chicken sandwiches!"

"I'm not eating. I'm going back to the clubroom. Take the train back yourself. Then, whether it's the chicken sandwich or something else, come to the school after you're done!"

"Come again? I can go, but why?"

"I have a task... Oh, by the way, bring your swimsuit, the one designated by the school."

"Sw-s-swimsuit…?"

Before Yuzuno could ask, Risome had already briskly walked into the blue passageway.

She had a bad feeling.

4
The Comical Grand Investigation

After lunch, following the request, Yuzuno headed to the clubroom. When she arrived, there were already three people in the room: Risome, Kaori, and for some reason, Sanae. The whole group was gnawing on popsicles around the low table.

"Hi! Yuzuno, how are you!" Kaori raised her hand first.

"Ah, I'm okay… Kaori, are you alright? You looked very tired yesterday."

"Oh, that's because I got up at four in the morning yesterday. I had a good sleep, and I'm fine now."

"Up at four…?"

"That's why I said don't worry about her."

After finishing his popsicle, Risome stood up with difficulty and threw the stick toward the trash can, but missed.

"Did you bring the swimsuit?"

"Yeah." Yuzuno raised the bag containing the swimsuit.

"Alright, then let's go outside. You can change into the swimsuit here."

"Okay… Hey, wait, I really don't understand your intentions."

"I'll explain the purpose when we get there. Just hurry up and change."

Even though she asked him for an explanation, there was another question mark hanging in the air. "There"? Where is "there"? And, "Why is Sanae even here?"

"Oh, Risome contacted me, and I had nothing to do, so I just…"

"Contact…?"

So, he contacted Sanae? But not long ago, he was furious and forbade her from coming here. Now, it's even more confusing.

The three of them left Yuzuno, who was in distress, planning to leave the room on their own. Yuzuno managed to throw one last question at Risome, who was closing the door: "There aren't any cameras or anything in this room, right?"

"…What do you take me for?"

"A guy who sneaks into the girls' restroom to secretly film girls' legs."

"Don't just look at people's faults!"

So, he also knows this is a fault.

"Alright, alright, change quickly. There's no time. Once you're done, come to the back of the club building."

The door closed mercilessly. Alone, Yuzuno sighed and helplessly began to change into her swimsuit.

The room was still like a steam box, but it was much better than yesterday. That was because two fans were added, blowing air from two directions. A quick look, and each fan had "Newspaper Club" written on them with a marker, indicating that Kaori had brought these from the newspaper club.

Yuzuno quickly changed into the school-designated swimsuit and wore her uniform over it. She didn’t know what this was all about, but decided to bring her towel and swimming goggles just in case. She left the room and, as instructed, circled to the back of the building.

On a small piece of treeless land on the north side of the club building, Risome and the others were waiting for her. There was also a new member, squatting on the ground surrounded by the three people, seemingly doing carpentry work. The monotonous sound of hammering was intermittent.

Yuzuno recognized the person's tangled curls. It was the drama club's director, Kajiwara.

"I'm ready with the swimsuit…"

"Here you are. Hey, is this almost done?"

"Just a moment. Almost… Oh, Hakata, long time no see." Kajiwara looked up and cheerfully greeted Yuzuno. The drama club and table tennis team both operated in the old gym, so they often ran into each other.

"Hello. What are you doing?"

"Ah, I don't quite know. Risome asked me to do it."

"Hey, you've stopped, you've stopped!"

"Oh, sorry, sorry."

Under Risome's urging, he resumed his work. After a detailed final check on the smoothness of the hinges and the overall strength, he handed the object to Risome: "It's done."

Although it was done, this item was completely lacking in decorative qualities and was evidently a simple makeshift product.

At both ends of a narrow wooden strip about 70 centimeters long stood a metal rod about 80 centimeters high. One rod had a hinge, and a door was attached to the hinge. On the top and bottom of this door, there were about 60-centimeter small wooden strips supported by several even shorter ones. The wooden strip closest to one side lay flat against the longer rod when the door was closed.

—This door, resembling a fence, seemed somewhat familiar.

"You're amazing! You finished it in just two hours since I called you over!"

"This level of stuff, we have to repeatedly make a lot every performance, it's a piece of cake!" The prop-centric drama club director gloated. Upon hearing Kaori's "thank you very much," he scratched his tangled hair bashfully.

"You're welcome, you're welcome. Risome's helped me before."

The help was probably referring to the incident at the old gym. Kajiwara was greatly involved in the case and coincidentally present during the investigation and identification of the culprit.

"…Still, even though I made it according to your request, I'm not sure what you're going to do with it."

"Nothing big, just planning to conduct an experiment."

"Experiment…" Yuzuno parroted the word Risome used: experiment. This fence. And, the swimsuit—

"No, you can't experiment! Absolutely not…" 

From these three keywords, Yuzuno deduced a conclusion she rather didn't want to come to. Finally understanding the situation, Yuzuno earnestly pleaded.

Risome, completely ignoring her attitude, issued a command: "Alright, let's go!" The group set off. Kaori held a large paper bag from a home store, Sanae took charge of the newly acquired DIY product, while Risome carried nothing.

Yuzuno threw a powerless smile at the good-natured Kajiwara, who waved lightly, then cautiously asked Risome as they passed him: "…So next, where are you planning to go?"

"The pool."

"The school's pool?"

"That's right."

"Your so-called experiment, could it be…"

"A field examination to test if the toilet paper alibi trick works. But, this is likely just temporary solace."

"Ah, I knew it…" 

The ominous premonition became reality.

"I'm asking you to play the role of the corpse, please!"

"Going to the trouble of changing into a swimsuit to play a corpse... this is awful!"

"It's not so bad. It's summer now, after all. Wearing a swimsuit is no big deal. If it were the frigid winter, now that would be awful."

"Your standard for 'awful' is beyond awful…" 

Yuzuno continued walking forward in defeat. What a hopeless day.

Crossing through the school building and passing the courtyard, they headed towards the pool beside the main entrance.

Standing at the entrance covered by a lattice door was a girl in school uniform. She had radiant long hair, beautiful fair skin enhanced by the contrast with her black hair, and captivating moist eyes.

This girl—Chizuru Yatsuhashi—noticed Risome and the others and silently handed over a clear file folder with only one paper inside.

"The pool use permit, valid until three o'clock. Clear the area for the swim team afterward."

"Oh, you've really helped me out, former vice president of the student council." Risome emphasized the "former" heavily. Chizuru’s classical Japanese beauty immediately twisted.

"…Since that's the case, please don't come running to me asking for pool use permits out of nowhere again. I'm not on the student council anymore."

The incident in the gym left a major impact on the students of Kazekozan. One of the outcomes was that she, known for her excellent conduct and third-ranking academic performance, voluntarily resigned from the vice presidency, citing her failure to prevent the murder as needing responsibility.

"I had to fabricate a suitable reason, apply for permission with the president at the staff office, then negotiate with the swim team… You need to consider how bothersome this is for me."

"Timidly asking for help really burdens someone. So sorry."

"Oh, you’re not troublesome. You’re actually quite willing to assist me, right?"

Facing Yuzuno's apology to the visibly displeased former vice president, Risome showed no intent of reflection. Listening to him, Chizuru shifted her gaze elsewhere unhappily and said, "… Well, I am willing to lend a hand. But your timing is quite pressing, please be more mindful in the future. You should never use school's facilities for personal convenience; that's also part of my principle…"

"Voice recorder!"

"Quickly go inside! Use it however you wish, you've got the permit!" 

A mysterious word. For some reason, her attitude changed abruptly, she forcefully opened the pool door, swiftly bounced to the side, and gestured for Yuzuno and the others to enter. She then coughed and said, "T-then, I’ll be leaving first. Clean up if you make a mess and make sure to withdraw by three!"

"Oh no, you should stay and help! I need manpower here."

"What? Why do I have to? I don't want to, why on earth must I…"

"Recorded…"

"Got it! Got it! I'll do it, alright?"

"…Yatsuhashi-san seems very odd." Sanae mumbled, glancing at Yatsuhashi, who was near tears.

Yuzuno wholeheartedly agreed: "…Risome, what have you done to Yatsuhashi-san?"

"Huh? Nothing, really."

Seeing Risome’s obvious attempt at dodging, more question marks popped up in Yuzuno’s mind.

Climbing up a short set of stairs, the group arrived at the poolside. It was the first time using the school pool outside of swimming lessons like this. The water lines were collected neatly by the pool walls, and the pool appeared wider than its actual 25 meters. Sunlight dappled the gentle water surface, producing dazzling reflections that made everyone squint.

Water, sunlight, and the scent of chlorine, along with the shouts of sports teams drilling on nearby playgrounds and the noise of cicadas.

The presence of summer was tangibly felt everywhere. As a way to spend an August holiday, this was fantastic—if you discounted the fact that only she was in a swimsuit, she was going to play the corpse, cooperating for an examination involving a murder case’s alibi device.

"Watch out, and guard against heart paralysis."

Accepting Risome's ominous advice, Yuzuno took off her outer clothes, leaving only her swimsuit, and carefully warmed up. She even doused herself with cool water from head to toe. Meanwhile, preparations for the "experiment" were underway poolside.

Kaori took out a small bucket, siphon tube, tape measure, thumbtack box, and a 12-roll pack of toilet paper from the home store’s paper bag; the brand, of course, was Joyce Paper’s "Ulysses," apparently requested by Risome. The simple opening part made by Kajiwara was placed right next to the pool. It was unstable, and without support, it would tumble, so Sanae and Chizuru held it on either side.

Risome lounged alone, playing with a stopwatch in the shade under the eaves. Yuzuno, shielding herself with a towel, approached and said, "I’ve showered off."

"Alright, let’s begin."

"…From the conversation and appearance, everything seems dubious, what exactly are you up to?" Chizuru asked, giving him a white look.

"It's not anything suspicious, just having Hakata rest against the door, wrapping toilet paper around it and pouring water on it, that's all."

"A fanatical role-play activity indeed."

"Not a role-playing activity, it's an experiment. We’re having this gal play the corpse." 

"Corpse enthusiasts really are beyond salvation!"

Risome paid no attention to Chizuru’s increasingly wary attitude, snapping his fingers to declare: "Good, let’s go. The murderer killed Amamiya on the horse path, scattered paper, and siphoned water from the opening onto the ground. Then they set a timer using toilet paper. I need to figure out the relationship between the length of paper wrapped, and the time it takes to dissolve. The one playing the corpse is Yuzuno Hakata. Alright, please."

"O-okay…" Responding to Risome's teacher-like tone, Yuzuno lowered her head. Kaori and Sanae offered scattered applause.

"Then let's start with a length of thirty centimeters. Kaori, if you please."

"Understood." 

Kaori measured out the length of toilet paper with a tape measure, tore it off, wrapped it where the door joined the railing, and finally pinned it with a thumbtack, then gestured for Yuzuno to come over.

"Um, what should I do?"

"Just sit against the door honestly."

Yuzuno placed her towel on a plastic chair and stepped into the sunlight. "Whoa—" Kaori and Sanae exclaimed.

"Yuzuno, you look so pretty! So slender!"

"Yes! You are a sight for sore eyes!"

"Stop it! And Risome, don’t keep glancing over here!"

"I'm not looking at you because I want to!"

This phrasing was rather offensive.

"But Yuzuno and the school-designated swimsuit are like Yoichi Abe's manga!"

"Still with these inexplicable comments…"

Yuzuno sighed again, then leaned on the door to imitate the pose of a corpse. The door didn't sway from her weight.

Kaori fetched some pool water with a bucket, then used a siphon tube to drop a small amount, simulating the leaky state. “Ready!” Risome gave a thumbs up, stopwatch in hand, and announced the start of the experiment like a film director, "First trial. Thirty centimeters. Okay, start!"

Simultaneously, Kaori, watching her watch, began to drip the water at the same interval as the horse path leak, one drop every five seconds.

"…Even now, I still want to ask, is it necessary for me to play the role of the corpse? Wouldn't it work if you did, Risome?"

With nothing to do but lean against the door, Yuzuno began to complain.

"That's not possible. Not to brag, but I can't swim."

"That's not brag-worthy," remarked Chizuru.

"However, there is a large weight difference between me and the victim—Amamiya-san. Won't this skew the results?"

"As long as we know how much paper it takes to support one kilogram, how many seconds it dissolves at, this will allow us to calculate accurately, no problem."

"I see." —No, wait!

"…Being able to calculate the value per kilogram means you know my weight, Risome?"

Yuzuno voiced her suspicion, to which Risome casually replied, "Yeah, I know." Yuzuno's face immediately turned pale.

"You-you, how-how-how do you even know that…"

"I asked your good friend."

"Sanae! You were the one who told!"

With this, everything clicked into place. Risome contacted Sanae for this reason. Yuzuno glared at her supportive friend holding the railing, who chuckled apologetically, saying, "Sorry, sorry. He was determined to know… What difference does it make? Your weight’s reason for pride, not embarrassment. Be proud!"

"Shut up! Close it! I'm going to kill you! Beat you to death!"

"Ah, don't, Yuzuno, you mustn’t move."
"You have to maintain this posture, okay?" Pfft. The paper supporting her body suddenly gave way. The door swung open violently, causing Yuzuno to fall along with it. 

"Ah!" She screamed, just like her older brother had once shouted, and fell backward with a splash into the pool. 

The cold sensation enveloped her entire body, her ears buzzed, and the long-missed feeling of being directionless in water returned, along with a vigorous resistance by flailing her limbs. It felt as if she had joined Marumi's dolphin team. As she struggled in the water, the sun's round silhouette still reflected in her eyes. 

"Yuzuno, are you okay?" She stepped onto the pool floor, raised her face above the water, and immediately heard Kaori's voice calling out. She gasped for breath and answered, "I'm fine." Risome, hidden in the shade, holding a stopwatch in one hand, calmly muttered to himself, analyzing the situation. 

"Hmm, both the paper and the body fell into the pool successfully. However, forty seconds is too short. The weight broke the paper first; could it be that we used too little? Increase it by ten centimeters next time." 

"...Doing it again?" 

"Of course. We have to repeat it many times to calculate the average." 

Yuzuno longed to just sink into the water and sighed without understanding why. 

Chizuru, who had been watching everything from the beginning, summed up the situation in one sentence: "...What is this?" 

The experiment was repeated several times afterward. The paper, gradually increasing in amount, finally reached a length that matched the actual situation. Then, to calculate how many minutes it took for the paper to dissolve, several more attempts were made. 

Yuzuno fell into the water about fifteen times. Various types of screams echoed periodically around the poolside. 

Ah! Yah! Oh! Wah! Oh! Ow! Ooh! Aiyah! Aiya! Oh no! Awoo! Waaah! Ahahaha! Wahahaha! 

"Well, I guess that's about it." By the time the director was finally satisfied, it was almost three o'clock. 

"Good job, Hakata Sister. I'll treat you to a popsicle and strawberry milk later." 

"Too, too cheap..." 

Floating in the water, Yuzuno helplessly complained about this unfair treatment. The endurance built through the summer's table tennis team activities was finally at its limit. 

"So, did you, figure, out anything?" 

"Wait a minute. Amamiya's weight is sixty-eight kilograms... We need at least a meter-long paper, and it takes eight minutes to dissolve completely." 

Risome reviewed Kaori's notebook used for recording, mentally calculating the result. 

"A meter, eight minutes? Hmm, so, to support a body firmly, you need at least a meter-long paper, and it takes eight minutes for it to dissolve, and the door to open?" 

"Yes. It aligns basically with our assumptions." 

"Then, doesn't setting the timer eight minutes before the body falls mean... Not at ten o'clock? The body fell at ten past seven, so it should be around nine fifty-nine?" 

"Under normal circumstances, that's how it would be." Risome said hesitantly to Kaori. Unaware of the context, Chizuru and Sanae asked from the side, "What do you mean?" To which they both shrugged, saying, "Nothing." 

Yuzuno floated to the poolside, pulled herself out of the water, and casually asked, "Is there a non-standard situation?" 

"Of course, there are as many as possible. The most probable one is: the perpetrator carefully wrapped more paper than the minimum requirement. In this case, the time from starting the device to the body falling would be longer. It could be ten minutes, or even fifteen." 

What was clarified was just a minimum value. It was impossible to determine that anyone with an alibi during this time wasn't the perpetrator. 

"However, if too much paper is used, evidence might be left behind." 

"...But, conversely, the time cannot be less than eight minutes, right?" 

"So, anyone with an alibi after nine fifty-nine is the culprit? Great, the range has narrowed! Hmm... Ah, no." 

Kaori's eyes lit up as she flipped through the notebook containing all the information but soon sighed with regret. 

Risome nodded and said, "Yes, there are a few with alibis after fifty-nine, but until fifty-nine, there's not a single suspect with a valid alibi. Moreover, even if you shorten the time to less than eight minutes, there's still a possibility to commit the crime." 

"Oh? How could that be done?" 

"For instance, pre-wetting the wrapped paper. Just this act could shorten the time it takes for the body to fall by a few minutes. If the perpetrator was premeditated and prepared everything, adjusting the time should be a piece of cake." 

--Even the eight-minute minimum was unreliable. 

Yuzuno and Kaori exchanged a glance and muttered almost inaudibly, "…If that’s the case, doesn't that make the experiment meaningless?" 

Chlorinated water dripped from her hair. Suddenly, the coldness of the water droplets seemed so meaningless. Falling into the pool as many as fifteen times, what was the point of that effort? 

"It is meaningful," Tama said, "We've proven that this trick is feasible, and the paper's dissolving time aligns with our expectations. Although the eight-minute minimum isn't absolute, it’s the most probable, serving as a benchmark." 

"Another benchmark? This morning, the same mistake was made." 

"That's what a benchmark is... it's progress." 

He was convincing himself rather than Yuzuno. As Yuzuno dried herself with a towel, he leaned against the wall in the shade, muttering softly. 

"Anyway, extending the time before the body falls is okay, but shortening it would only disadvantage the perpetrator. It's unlikely. No problem; we can trust the eight-minute limit. But there are still eleven suspects..." 

Yes. The result was that the suspect range hadn't narrowed. Consider it comfort—Risome said, indicating he had already understood the test would merely confirm things before the experiment began. 

"Is there hope to solve it?" 

"I don't know. Hopefully, we can find more clues." 

As Kaori expressed her concern and Risome folded his arms, Chizuru poured a bucket of cold water on their conversation: "Sorry to interrupt your serious talk." 

She carried a bucket full of water from the tool area and placed it in front of Yuzuno and the others. Nearby, Sanae stood with a floor brush in hand as instructed. 

"On the poolside and in the water, there’s undissolved toilet paper. Please clean it up quickly, will you?" 

"...Is this our job?" 

"Isn't it? You dirtied it." 

"But this permit here has your name on it. This means you are the borrower and the responsible person." 

"Weren't you the one who told me to borrow it? Anyway, time is tight, so please hurry and clean up!" 

"Recor..." 

"No choice, I'll do it for you guys!" 

Just a word made Chizuru instantly compliant, rushing forward with the bucket in hand. She sighed miserably, "Darn Risome—!"—It was suspicious after all. 

"Ri-Risome, I don't understand what's going on, but we should do the cleaning. We shouldn't force Yatsuhashi to do it." 

"It's fine, let her do some work." 

"How can you say that..." 

Why was Risome so harsh on her? Yuzuno looked at Kaori, but she just tilted her head in confusion. 

"...I don't understand what's going on. Anyway, let's help her." Sanae said smartly, hugging the floor brush and going after Chizuru. Yuzuno, fed up with Risome's nonsense, roughly tossed down the towel and followed Sanae. 

"I'm not going to say anything else, we'll help too." 

"...Wait!" 

"Not waiting. If you want to go back, go ahead!" 

"Wait!" 

"You keep making us wait! You're too mean, that's it, or I'll be mad..." 

Yuzuno was stunned as she turned back. What stunned her was catching sight of Risome's eyes. 

His eyes were pitch-black, with no light, seemingly drawing people in and destroying them. 

Risome didn't move an inch. However, the darkness in his eyes quietly swirled deep within them. 

The coldness from the water droplets all over her body vanished somewhere. The scorching sunlight on the back of her neck, the sound of cicadas, the cheers of the sports team, even the surrounding scenery all rapidly faded away. Yuzuno felt as if she were diving into the water again, lost in the murky depths, confused by this deep, night-like color. 

This strange sensation lasted until Risome took a step and passed by her. Suddenly, the summer heat and the dampness of her swimsuit came back. 

"...Ri, some?" 

Though Yuzuno called out to him, he didn't respond. He quickly circled around the poolside, approaching the former vice president, who was about to start cleaning. Chizuru raised her head and noticed the urgency on Risome's face, voicing her confusion aloud: "Wha-what's wrong..." 

"Yatsuhashi, you were carrying the bucket, right?" 

"Yeah, I was. Didn't you tell me to do the cleaning?" 

"How did you carry it?" 

"Huh? How else? Just carried it normally." 

Chizuru grabbed the bucket handle, lifting her arm to show him. Risome stared at the bucket and then reached his right hand into the water. 

"Wha-what are you doing?" 

He still didn't answer, withdrew his hand from the bucket, raised it to his waist, and stood still. Yuzuno and Kaori also walked over, only to see him observing the water droplets dripping from his fingers. He stared intensely at the watermark on the ground, about three centimeters in diameter, without blinking. 

"Yatsuhashi..." After a while, Risome said briefly to Chizuru, "Well done!" 

"...What are you saying? I don't get it." 

"Don't understand? No, now I get it, it can't be wrong. Ah, I was really foolish not noticing something so obvious... right... right... it must be like this." 

Risome nodded repeatedly in affirmation at the water surface in the bucket. The four girls around him watched with varied expressions, Chizuru frowning, Sanae looking confused, Kaori acting like she was used to it, while Yuzuno remained on edge, worried. 

"Um...Risome, are you okay?" 

"Of course, I'm okay. Hakata girl, you can go change your clothes. We'll help with the cleaning." 

His unserious and mean spirit suddenly vanished. He took the bucket from Chizuru's hand, making her even more cautious. 

"What? What? Are you going to help in the end?" 

"Yes. To thank you for making me notice this. Kaori, Nonami, you guys help too!" 

"What harmony!" 

"As if you need to say it?" 

He pushed the process forward without waiting. "Since that's settled..."—Yuzuno, despite her remaining doubts, returned to the shaded area where the towel was laid. 

She heard Risome muttering almost word by word, "Four people—so now there are four remaining." 

5. The Second Sister

Since there was no way to wear clothes over a wet swimsuit, Yuzuno draped a towel over herself and quietly made her way through the school building. Once she returned to the "locked activity room," she immediately sat on the bed and sighed, "I'm exhausted..." 

Summer vacation, a Sunday with no training. It was truly a well-deserved day of rest. But since early morning, she was ordered around by Risome. On the bright side, she got to wander around the aquarium as if she had it to herself and saw adorable dolphins. That's about it. On the other hand, the disadvantages came one after another. First, she was teased by the staff because the cameras caught her legs, saying she was on a date, and in the afternoon, she played the corpse role, falling into the pool up to fifteen times. She was also seen wearing a swimsuit by Risome, had her weight revealed by Sanae... And the important deduction work was a waste of effort; the investigation became trivial, filled with uncertainty, and had no way forward. 

Just listing them one by one felt exceedingly stupid, and Yuzuno swayed and collapsed onto the bed. The lightweight rebound of the spring transmitted to her upper body. Her hair wasn't dry and might wet the sheets, but who cared about that now! 

"...They said it was meaningful, but was it really?" 

The mopping and bucket deduction that didn't match, the questioning at the aquarium that deepened the mystery, and the ridiculous experiment just conducted from start to finish. 

Everything seemed in vain to Yuzuno, and the more she thought about it, the less energy she had to get up from the bed. Although she wasn't Risome, she genuinely wanted to throw a blanket over herself and sleep right then. 

—Or maybe, it could be possible advancement as he said? 

He finally said: four people. That meant, four people remained. 

If that number referred to the suspects, then the investigation would have made significant progress. Just a minute ago, there were as many as eleven suspects, suddenly reduced by seven people. 

Risome's behavior at the poolside was clearly peculiar. Just like the last time solving the case, he suddenly had an awakening and quickly broke the case. It's likely he realized something this time, too. He even praised Chizuru, "Well done," and thanked her for "letting me notice this." 

But—exactly what did he notice? 

He inquired about the method of carrying the bucket. Could such a normal act be a clue? 

Yuzuno stared at the ceiling, recalling Risome's eyes at that moment again. His widened eyes, reminiscent of deep underwater. 

In this place devoid of any light, nothing could be seen. 

Risome always hid the core. Deceiving the police, fooling suspects, lying to Yuzuno without batting an eye. She had once asked Risome how much of what he said was genuine, but only received a perfunctory response. Whatever was in his mind, whatever internal journey he experienced, Yuzuno remained entirely unaware. 

Such as this room. Why did he live in the activity room? 

"…Uh-oh!" 

Yuzuno looked around the room, coming back to her senses. This wasn't the time to daze off on someone else's bed! 

She sat up, reaching for the swimsuit strap in front of the still-running fan. The sun had reddened her already delicate skin, making it sting upon touch from sitting by the poolside far longer than actually being in the water. 

Yuzuno wanted to carefully remove the swimsuit to avoid hurting her skin. But if she was too slow, there would be another problem. How long would it take to clean the pool? If she didn't quickly change her clothes, the room's owner might come in at any moment. 

Creak, creak. 

Yes, a sound like that. 

"...Huh?" 

No way? By the time that thought crossed her mind, it was already too late. What she heard wasn't a knock, but the sound of a key turning, and in the next instant, the door was pushed wide open. There wasn't even time to stop or cover, and Yuzuno and the visitor locked eyes in surprise. 

"...Huh?" 

Once again, a voice of confusion echoed, this time in a duet. One was from Yuzuno, and the other was from the stranger. The person who opened the door wasn't Risome, nor Kaori, not Sanae, and certainly not Kajiwara or Chizuru. 

It was someone Yuzuno had never seen—a petite girl wearing a navy blue uniform. 

Her uniform was a shade darker than deep blue, almost black, with red stripes along the cuffs and lapels. It was the uniform of Hiten Academy, which she had just seen the other day. Heavy paper bags and plastic bags hung from the slender arms of the girl. 

Her black hair was tied next to her left ear, draping over her shoulder and in front. A large decorative charm with a musical note pattern hung from the rubber band, with its golden part reflecting the sunlight with a shiny glimmer. 

Among her youthful features, the only slightly mature, lively double-lidded eyes left an especially deep impression on people. 

Like her uniform, her eyes also seemed familiar to Yuzuno. 

"...Um, who are you?" 

After a brief moment of awkwardness, Yuzuno asked the girl. The other replied, "I'd rather know who you are exactly, and why you're in this room, in such a... provocative..." 

Then, suddenly realizing something, she entered the room and closed the door. She likely did this to prevent anyone outside from seeing Yuzuno's upper body, half-exposed from undressing her swimsuit. If possible, Yuzuno wished she would leave as well. 

Anyway, Yuzuno took the opportunity to quickly change her clothes. The girl, red-faced, stood by the door watching her. 

"Uh, sorry. How embarrassing."
"“No, no, that's not true. You're pretty and lovely. Hmm, if needed, can I help you?”

“Ah, no problem. Sorry...”

What kind of conversation is this? What's going on here? As Yuzuno got dressed, she asked, “Are you... Risome's... acquaintance?”

“Risome? Risome Tenkma? The useless guy living in this room?”

“Yes, that Risome.”

Knowing both his living situation and that he resides here, it was clear she was an acquaintance.

“Does that mean you also know him?... Could it be that he made you do this?” The girl pointed to the swimsuit Yuzuno had just taken off.

“Oh... yes, it's kind of that situation. Though it's complicated.”

The girl ignored Yuzuno’s explanation. She tossed a bag onto the floor and bowed her head, trembling all over. She whispered a curse filled with resentment: "This, this guy, having Kaori isn't enough, he also flirts with such a pretty girl and even gets her to wear a school swimsuit... Ah, too despicable, unforgivable! A person whose behavior is like a beast, how should you be dealt with..."

"Are you okay?"

"Huh? Oh, of course."

The girl looked up with a smile.

“So you’re friends, then. I appreciate you taking care of my brother. Right, how about I fold this swimsuit?”

“Oh, no need, I’ll do it myself... Huh? Did you just say 'brother'?”

At that moment, there was a knock at the door outside. It was Risome's voice: “Hakata-chan, are you done?” Yuzuno quickly shoved the swimsuit into a bag and replied, “Come in.” The door opened, and the owner of the room returned to face the girl.

“Oh, you’re here.”

Risome didn't show any signs of surprise.

“Mm, Risome, this person is...”

“She's one of us, don't worry.”

“I'm his sister.” The girl finally introduced herself. She bowed slightly to Yuzuno, her tied-up hair adorably swaying: “I'm Risome Kyouka, nice to meet you!”

“This girl, your sister? Risome's sister? Doesn't look like it at all,” Sanae bluntly asked.

“Huh? Really?” said Kaori, “I think they look quite alike. Kyouka and Tenkma have the exact same eyes.”

“Appearance-wise, maybe, but Kyouka is polite, clearly a decent person.”

“Don't insult me so subtly." Lying on the bed, Risome frowned. Four girls surrounded a short-legged table, leaving no seats for him, so he was forced to his usual spot—the bed. As the room became crowded, the long-closed windows were opened, allowing fresh air to flow through.

“Besides, this guy isn’t as straightforward as he appears. His mind is the most malicious.”

“That’s not true, Kyouka is very cute, so she'll forgive you.” Kaori’s comment came slightly delayed. At the same time, she poured a glass of Calpis for Kyouka. Accepting it politely, Kyouka said, “Thank you very much!” Then told Risome, “Stop saying baseless things to people meeting me for the first time. Or I'll kick you.”

She glared at Risome fiercely. Yuzuno sipped her Calpis, thinking—Indeed, different from a decent person. Risome Kyouka, Risome Tenkma’s sister.

She had heard about his sister shortly after meeting Risome. He mentioned having "parents and a sister" living one station away from Kazekozan. But she didn’t know that this real sister would visit her brother’s place.

No, usually, it’s natural for a sister to visit her brother…

“It’s you who’s malicious. Even if it's at school, you brought three girls into your room. Two weren’t enough, so you brought such an active girl to serve you, and even made one do such shameful... Though I'm glad, it’s wrong, immoral, a damn beast!”

“What are you saying?” Kyouka's gaze quickly swept over Yuzuno and Sanae. If told that she was recently a traditionally Japanese style beautiful girl, no one would believe it.

“They came on their own! I didn’t bring them.”

“You paid them?”

“Why do you always think so filthily? No, it’s not like that... huh? Why are the sheets wet?”

“Ki-Kyouka, that's the Hiten Academy uniform, right?” Yuzuno, trying to avoid exposing the wet sheets, hurriedly shifted the topic to Kyouka.

“Mm, I’m in third year of middle school. My extracurricular activities just ended, and I was about to go home.”

“You study at Hiten. That’s amazing, you must be clever!” Yuzuno realized immediately that as Risome's sister, she'd certainly be smart.

“I'm not that smart... That kind of school is strict and just boring.” Playing with her red scarf, she leaned closer to Yuzuno and said, “Speaking of clothes, Yuzuno Hakata... right? Why were you taking off a swimsuit here? I heard it was my brother’s request.”

“Ah, well, that's because...”

“It's for table tennis training?” Kaori promptly diverted the topic. “Training? Wearing a swimsuit? It wouldn't happen to have ‘evening’ as a modifier, would it?”

“It's broad daylight. It's a practice method for a finishing move. Using a towel against the water flow makes the ball spin rapidly. Tenkma came up with it, right?”

“Mm, back then, Kaidoh-senpai in ‘The Prince of Tennis’ did similar training.” Lying there, Risome deeply agreed. Kyouka stared skeptically at Yuzuno. Yuzuno felt her thin arms had become Kyouka’s reasoning clues and instinctively hid them behind her.

“...It seems odd. But, alright then. Speaking of which, Yuzuno in a school swimsuit reminds me of Youichi Abe’s manga.” After expressing understanding, Kyouka echoed words similar to her brother's. They truly were siblings.

“In any case, Hakata-san and Nonami-san should be very careful. My brother has a nasty personality. I always see that.”

“You’re too nosy. Also, stop using 'brother' like that. That character setup is cringy.”

“That’s not a setup!”

“Alright, alright. Fine, just leave it at that.”

Risome sat up, poured himself a Calpis, took some ice trays from the fridge, and skillfully put a few cubes in. The sound of ice clinking against the glass was like wind chimes.

“I'll forgive you for badmouthing me or calling me ‘brother.’ I feel great now, as if what was stuck in my brain is gone.”

“The expression is ‘stuck in my throat.’ What are you saying...”

His sister was speechless, but Yuzuno figured out his meaning. Describing it as “stuck in the brain” was accurate. Risome must have found something decisive by the poolside.

“...By the way, why did you come today?”

Asked his brother, as Kyouka sipped her Calpis—holding the cup in her palms like hot tea—and picked up the paper bag beside her. “This was delivered to our house again. All addressed to you, brother.” The open bag revealed a box from online shopping. Similar boxes were scattered around the room.

“Oh, I see. Sorry, sorry. Though I notified the Black Cat courier office, other companies I haven't.” Risome muttered curiously as he took the bag. More delighted even than when things were unstuck from his brain appeared.

“This was given by our mother, she brought chikuzenni.”

“Oh, that's wonderful.” Inside the translucent box were bamboo shoots and carrots. From the way they addressed the brother to the menu of care packages, Risome's family was evidently very traditional. That reminded her that the breakfast he ate in the car that morning was red bean rice dumplings.

“Our mother gave this too. Your living expenses for this month.” Finally, she handed him an envelope. Risome's face shone brightly. He lunged to grab it, and Kyouka immediately withdrew her hand.

“Let me remind you, these are living expenses. Don’t spend them on frivolous things.”

“Got it! No problem. I’m quite flush right now.”

“Really...?” Her youthful face twisted with doubt. Judging by the conversation, she didn't seem to know Risome's side job. “All talk.” Kyouka grumbled but still handed the envelope.

“Because you live here, please make sure to live properly. Our mother worries a lot, fearing you don't tidy up, the AC breaking leaving it like a sauna, the fridge holding only bean paste and jam, etc.”

“Ah... uh, it’s fine. For now.” The mother's keen insight made even Risome shrink back. With a bit of admiration, Kaori added, “Incredible...”

Kyouka surveyed the messy room and said, “From the looks of this mess, it’s hard to believe everything’s fine... You still have tasteless hobbies.”

“What makes you think my hobby is tasteless?”

“Huh? Just that lowly people like you, brother, can’t grasp the sublimity of my hobby.”

“I can understand. Recently, I started liking Sunflower-san.”

“Admittedly excellent. But, the theme progresses slowly, not aligning with what I seek. It's better to have special charm like Himiko and Chikane.”

“You're the one with low taste!”

The bewildering conversation continued for a while. Acting as silent spectators, Yuzuno and Sanae tiredly lamented and munched on their dessert konjac jelly.

After a span, Kyouka concluded, “I still can’t understand my brother,” and rose to leave. “Well, my job here is done. I’ll take my leave... oh, by the way, the new tune will be complete soon. I’ll need your help when it’s done.”

“What—?”

“Kaori, let’s hang out next time.”

“Mm, I’ll look forward to it.”

“Hakata-san and Nonami-san, see you! Hakata-san, to make up for my brother, I’ll wash the swimsuit.”

“No, it’s fine. I’ll wash it at home...”

Saying goodbye to everyone, Risome Tenkma’s sister left the room. In the end, Yuzuno couldn’t figure out if she was polite or unbecoming, or both? Polite, yet not straightforward.

“Kyouka’s still so interesting,” Kaori said contentedly, holding her Calpis. “Kaori, you’ve known her previously?”

“A long time. We often played together, the three of us. Right?”

Sometime during, Risome returned to the bed and grunted “forgot,” turning towards the wall.

“Wow, feels like a lot of information...” That was Sanae’s impression. Indeed, this brief visit revealed a lot about Risome’s background. A sister attending Hiten Academy, traditional family values, a perceptively strong mother. Apparently, living expenses were still provided by parents. What was the final “new tune” about? So many mysteries—hold on!

“Sorry, I need a minute.”

Yuzuno pretended to go to the restroom in the activity building and left the room.

This was her opportunity, she thought.

She searched around and finally spotted the black-clad figure moving between school buildings. Forgetting the poolside fatigue, she hurried to catch up. She crossed the yard, entered the slope toward the main gate, and reached an audible distance.

“Kyouka! Please wait!”

The small figure turned and stood still. Tree leaf shadows netted on the asphalt surface. The two girls finally faced each other.

“Hakata-san? What is it?... Ah, were you going to give me the swimsuit?”

“No, it's not that.”

“Then, exchanging email addresses? Yes, rather than a swimsuit, what we need is to understand each other better.”

“No, that can wait... I have something to ask you.”

Yuzuno steadied her breath and continued.

“—Why does your brother live in that room?”

This was the biggest mystery.

Living in the school’s club room. His home was only a station away, and he had a family, yet even with a broken air conditioner or a fridge full of only jam and paste, he stubbornly didn’t return home. The key point was his family allowed this, even providing him with living expenses.

Such circumstances were clearly unreasonable.

Whenever she asked Risome or Kaori, their response was always, “It's complicated.” Complicated, what's so complicated? What kind of situation is Risome's family in?

Really want to know.

Really want to understand the side he always hides, even if just a little.

“...Oh, of course, if it’s unspeakable, forget it.”

“You don’t know?”

Kyouka widened her eyes in surprise. This reaction surprised Yuzuno as well.

“Since you have free access and were even playing school swimsuit exhibitions, I thought my brother had already told you.”

“Uh, no, I don't really know yet. Also, that wasn’t an exhibition.”

Regardless, Yuzuno took a step closer.

“Can you tell me?”

“There’s nothing special to tell. It's simple. He has nowhere else to live.”

“...Huh?”

A breeze squeezed through the summer heat, wafting past. The scent of rain swept between them. Coldness reminiscent of swimming revived.

Leaves above rustled noisily.

“But, how can he have nowhere to live? Doesn't Risome have a proper home…”

“Oh, you didn’t know that either. My brother can’t go home. No, to be precise, he won’t go home.”

“Why?”

Kyouka’s hair ornament sparkled as she still wore an innocent smile and said, “Because my father broke off the parent-child relationship with my brother.”

In Japanese, the pronunciation of karaage chicken sandwich is a homophone with ‘cowardly wins three times.’

A magazine about Japanese voice actors.

The name of this crab in Japanese is Yunohanagani, and the first two syllables sound like “Yuzuno.”

The dolphin from “Seven Seas' Tiako.”

Pink dolphin named Luffy in “Doraemon: Nobita’s Great Adventure in the South Seas.”
Chapter Five: Too Many Suspects and Too Few Clues

1. The Crazy Family Chronicles

Since no one responded after a few knocks, Yuzuno used the key she had to unlock the door. Her arm, wrapped in the long sleeves of a summer sun protection shirt, opened the door.

The temperature had become similar to early autumn. A thin layer of clouds covered the sky, dampening the sun's intensity. On the morning of August 6th, it was comfortably like the previous days were just an illusion.

The activity room had returned to a pleasant temperature. The rhythm of the occupant’s life had also returned to normal, with breathing sounds still coming from under the blanket. Yuzuno boiled water with an electric kettle and made two servings of instant coffee. When she opened the bag of sliced bread she had brought, it woke him up.

"...What time is it now?"

"Eleven o'clock."

"Eleven... What are you doing so early?"

"Preparing breakfast. Also, eleven o'clock is not early; it's already morning. You only have soybean paste and jam here, so how about a jam sandwich?"

"I don't want to eat something sweet first thing in the morning."

"Then should I use the soybean paste?"

"No real choices, huh..."

Tama slowly crawled out of the futon and sat at the low table. Although he was sipping coffee, he still looked half-asleep, with a few strands of hair sticking up at the back of his head.

Yuzuno handed him the breakfast she'd just made—a slice of bread with strawberry jam on a plate. "You should have removed the crust," he complained while eating, then suddenly seemed to remember, "Oh, right, why are you here? To make me breakfast?"

"Of course not."

"I thought so... What are you here for, then?"

"Well..."

Yuzuno hesitated, unsure how to begin.

"Yesterday, the conversation got cut off halfway, and there are things still unsaid, well, sort of."

"Unsaid?"

"Severed, severed..."

"Severed?"

"Uh, well, it’s..."

It's better not to ask. Yuzuno lowered her head and blew into her mug. The heat dissipated, causing ripples on the surface of the black liquid.

—Risome, did your father really sever ties with you?—

Such words were too difficult to voice directly to the person involved.

Severance (duan jue) ① To punish according to the crime. ② To rebuke. ③ To sever the master-servant, father-son, teacher-student relationships and expel. (From "Kojien Dictionary")

This is a term almost unheard of in this era. Severing relationships and expelling. Risome's father had cut ties with him. Moreover, based on the phrase "to be precise, it's that he doesn't come home," it seems Risome himself also wishes to sever ties with his father. It can be inferred that his relationship with other family members seems normal, but with his father, it's completely severed.

Why is that? Yesterday, after Yuzuno learned about the situation from Kyouka's mouth, she wanted to ask further questions. But she did not succeed. Because the wind grew stronger and rain clouds began to drift in.

She said, if it rains with thunderstorms, it would be troublesome, and quickly walked downhill (yet she didn’t forget to excitedly exchange email addresses with Yuzuno). When Yuzuno returned to the activity room, Kaori and Sanae were already getting ready to go home. The rain started just before Yuzuno got home. Although it soon lightened up, it continued to drizzle into the night.

Thanks to this, today was so cool. However, the sudden evening downpour not only turned Yuzuno into a drenched rat for the second time but also left doubts and time for thought brought by the unresolved questions.

—Having no place to live, thus residing in the activity room.

Startling, truly startling. But also understandably—the reason is quite understandable. When she first heard he didn’t return home despite having one, Yuzuno might have already identified this answer subconsciously. Therefore, even though he was clearly violating school rules, Yuzuno never thought to expose him; during her detective dealings with him, she subconsciously avoided negotiating using his biggest weakness—living in the activity room.

On the contrary, she directly critiqued his lifestyle—stubbornly opposing his parents yet still relying on them in a manner typical of people who latch onto their parents. She agreed to provide him with funds for independent living to reach an agreement.

But recalling now, during the negotiation in late June when she first asked for his help to solve the gymnasium case, there were indeed disagreements.

Yuzuno asked at the time, "Your parents don't agree with you living here, do they?" But it wasn't Risome who answered; it was Kaori. Moreover, Kaori's line was, "Generally, they wouldn't agree, right?" It was simply a judgment on general circumstances. When Yuzuno presumptuously decided that his parents didn't agree and continued scolding him, Risome seemed to reach his limit and stood up. Then, just as he was about to speak, he heard Yuzuno's proposal of "paying money," which silenced him.

At that time, Risome wasn't denying Yuzuno's proposal. What angered him was Yuzuno presuming he had left home willfully and recklessly.

Additionally, the part about "relying on parents"—Yuzuno criticized him for not handling it thoroughly enough. It wasn't thorough, but when a father and son severed ties while the mother and sister secretly went against the father's will, it's an entirely different story. For Risome, Yuzuno's actions touched the core family issues he least wanted exposed, so he was deeply annoyed?

That whimsical manga-version negotiation on that day suddenly revealed an entirely opposite side. Yuzuno spent the final part of that well-prepared rest day in bed, regretting everything. She truly loathed herself.

Fortunately, Risome seemed to have forgiven everything, perhaps because he received a living expenses fund of 100,000 yen and didn't mind. But Yuzuno still wanted to apologize. With that intention, she visited Risome early in the morning for two consecutive days. However—

"'Severed' what? Severance? Intermittent? Severance Bridge meeting?"

"...It's about the aquarium case. How's the investigation progressing?"

"Oh, that."

Despite having bought bread and come running, she still couldn't take the final step. Yuzuno felt unable to take this step, so she inquired about another matter she was curious about.

"You seemed to have discovered something by the pool yesterday."

"Yeah. Well, to say discovery, there indeed was something. But then it led to a dead-end..."

He averted his gaze and took another sip of coffee. His tone was quite different from yesterday, vague.

At this point, a soft knock came from the door. Knock, knock, knock-knock-knock—this distinctive rhythm was Kaori's signal for entry.

Come in!—Upon hearing Risome's voice, there was a startled exclamation from outside: "Ah, it's not even a Sunday, and you've already woken up in the morning, Tenma! Unbelievable!"

"Can't you even keep your self-talk quiet?"

Risome remarked upon hearing the unlocking sound. Yuzuno chuckled; it was very Kaori-like.

However, she wasn't alone.

Once the door opened, Yuzuno noticed a tall man standing behind Kaori. Risome choked on his bread, but the man ignored it, said “Excuse me,” and stepped indoors after taking off his shoes.

It was Inspector Sendou.

2. A Body Hardcore Even for the Experienced

"I was on my way to the newspaper club and thought I’d stop by you. Unexpectedly, I happened to run into Inspector Sendou in front of the school building."

"In front of the school building… did something happen?"

"A report came in saying some fool was living in the school without permission."

Sendou quipped. This was his second time here. The first was the day after solving the gymnasium case. He had come the first time with Yuzuno's brother, and they struck an agreement as a reward for Risome solving the case to overlook Risome living within the school.

"Even messier than last time. Clean up a bit."

"Yeah! Risome, you see, clean up!"

"It's cleaned up well. Just too much stuff."

Risome stubbornly stuck to his viewpoint. Then he asked Sendou, "Is there something you need from me?"

"Uh... well, nothing major."

Sendou appeared even more exhausted than yesterday. Dark circles under his eyes, and his gray suit matched perfectly with his hair, was wrinkled. Accepting the fresh coffee from Yuzuno, he said, "Thank you." The gratitude in his voice was lethargic.

"I got in touch with Officer Shirou from Hodogaya Station about the air conditioning. He’s quite eager to help, saying they'll come with staff around three o'clock."

"Oh, I see, understood! Finally, we can say goodbye to this scorching hell!"

"It’s not that hot now, is it?"

"They say it’ll exceed thirty degrees in the afternoon!"

Hearing Yuzuno say this, Sendou added. The weather forecast indeed mentioned afternoon temperatures resembling midsummer. Just learning about this, Risome lowered his head in irritation: "That's terrible..."

"Find another spot to cool off, won't you?"

"Yeah, Tenma, let’s go to the aquarium! Take me this time!"

"Aren't you on your way to the newspaper office?"

"I can just say I need an additional interview."

"Now I appreciate Kuramachi's hardships... So, detective, did you come just for this?" Risome lifted his head, and the inspector slowly moved his hand to his chest, pulling out a stack of photos and several plastic bags.

"These are the autopsy reports that arrived this morning."

"...Hey, I didn’t expect you to deliver them personally. I thought you disliked me."

"I really dislike you. Your insight is indeed sharp!"

Another jab at Risome.

"But, more importantly, solving the case comes first. Besides, it seems like you've got new ideas; listening won’t make me lose anything."

From his pained expression, it was clear the investigation led by Yuzuno's brother had stalled.

"By the way, I also have something to ask. Have you inspected everything placed in the rooms in the rear courtyard of B Building?"

"Of course, everything was checked once the case occurred."

"Oh, I see. Really, if I’d asked you first, there wouldn’t have been an infirmary incident... never mind. Truly speaking, there aren’t any towels or cloths in the office for wiping, right?"

"The office? Oh, right, certainly not. Office-like rooms are structured simply, with nothing a zookeeper would use."

"I see. That's great. Thank you!"

Funami had said, "There are no items for wiping in the office", it seemed this testimony was confirmed. Unclear of Risome's intent, Sendou tossed the stack of photos onto the low table.

"Look, these are photos of the body and the items encountered. If you want to see, I'll let you see."

"I don't want to see."

"I’m ordering you to look! It's part of the procedure!"

"I’d rather not see what's been inside a shark's... wah-wah-wah..."

Sendou, regardless, laid the photos out before him. Risome groaned and glanced downward. Behind him, Kaori took a peek and immediately turned pale, leaning forward. Sendou reassured, "The body is quite hardcore; it's best for girls not to look."

"Even for guys, it's best not to look at this!"

"You're from the video game generation; you should be quite adapted. Don’t you play games where you battle zombies?"

"I don’t. I’m terrible at games requiring operation skills, as I lack reflexes."

Kaori ignored their conversation, called "Yuzuno," and buried her head in Yuzuno's chest. Yuzuno, stroking her head, couldn't resist looking at the terrifying object’s edge.

A ghastly pale body color was not even slightly similar to the healthy skin she saw in photos yesterday. A watch, the same thickness as a wrist, had its hands stopped at ten past ten—that was when he fell into the tank.

"This half is the upper body found in the shark's stomach. It’s a surprise it’s preserved in its original form. Here’s the lower body left in the tank."

Sendou began explaining.

She shifted her gaze to the leftover items in the plastic bag. A completely soaked notebook and a small accompanying pen. A radio-controlled aquarium-standard watch with a neatly snipped strap. Also, two dog whistles on strings.

One of the strings was red.

"It's clear on two points: the victim was already dead before falling into the water, and the cause of death is a wound on the neck. However, other situations are unclear, with severe lacerations."

"Upon seeing it like this, indeed. Are these the items found? I see there are two dog whistles."

"It's likely a training dog whistle—one of them belongs to Tomoka Takino, right?"

Yuzuno recalled what Tomoka said yesterday: "It seems Mr. Amamiya might have taken it." Her guess was correct.

"It could've been worn like a necklace around the neck, tucked inside clothing. I heard it was tangled with the body."

"... Huh? Was this also found inside the shark?"

"Oh, of course. However, the notebook was found in the trouser pocket."

The "however" didn't make it sound any better. Feeling increasingly nauseous, Yuzuno hugged Kaori for comfort.

"Any findings on the notebook? Like the previous case?"

"No, the ink's all washed out, not a word visible."

Frowning, Risome confirmed the photos and remnants one by one. Sendou leaned in and asked, "So, any discoveries?"

"No, just feel sick."

This genuinely honest reply was too honest.

"What do you make of Takino's dog whistle? Share your perspective."

"Not sure. Is it really an act by Amamiya like Takino suggested, a prank, or is it the murderer trying to incriminate Takino by deliberately placing it on the body? It's hard to judge."

"...I made this trip for nothing."

Just like Yuzuno earlier, Sendou sighed deeply into his coffee. "But I didn't expect much anyway."

"I wouldn't have thought you'd say that. We have made progress."

"You make it sound like we haven’t."

"Progress?"

"...Currently, Hakata is doing tests at the investigation headquarters. Toilet paper..."

"That, the limit is eight minutes."

Poof—Sendou sprayed coffee. "You’ve investigated this?"

"Checked in the pool... anyway, no matter how many steps forward, the end isn't visible."

Though the investigation had made progress, narrowing down suspects, it was still a dead end with no clue to the real culprit's identity.

Risome rested his arms on the low table, supporting his head, and said, "I'm getting tired of it. Too many suspects... or rather, too few clues."

As he spoke, he drained the remaining coffee in his mug.

The coffee was no longer steaming.

3. Pre-Show Before the Show

"In the end, why am I here again?"

An hour later, they looked through acrylic at water snakes eye-to-eye.

"Isn't it nice? It's so cool here."

"Besides, without coming here, you can’t investigate the case at all."

"You can’t investigate even here..."

Risome shifted his gaze from the tank to his surroundings. The aisles were crowded. The shouts of elementary school kids, the cries of infants, the loud conversations of aunties, along with the laughter of middle school students. Various noises overlapped, turning what should be a deep-sea-like atmosphere into a shallow beachside.

—Building B remained closed, but business had resumed as usual starting today.

Upon hearing this from Sendou, Yuzuno and the others (mainly Kaori) were restless and dragged Risome into the police car by persuasion and coercion, arriving once again at Marumi Aquarium.

After both the murder and the accident, the resumption of business might not attract visitors—but contrary to their ideas, many tourists queued at the entrance, and great effort was required just to find a parking spot. The inability to access Building B led to Building A being more crowded than usual.

"It's too noisy, let's find a place to rest."

"Yuzuno, look, a moray eel! A moray eel!"

"Huh? Where? In the pipe? Ah, indeed! So cute!"

"I can go home now, right... yo!"

"Oh my, Detective, you're here again today."
"Two people squeezed through the crowd to greet him. They were Izumi and Director Nishinozu, both still wearing yellow polo shirts today. 'I'm not a detective. Congratulations on resuming operations!' 'Ah, thank you, thank you. Everyone's been very supportive...' 'A bit too supportive, there are too many people. Is there a place to rest for a while?' 'We're heading to the performance pool next, are you coming today too?' 'We are, absolutely!' Yuzuno, still excited from the dolphin show, loudly agreed to Izumi's suggestion. Hearing the chance to catch up on the dolphin interview they missed two days ago, Kaori was also visibly pleased. 'According to the original plan, reopening was still a long way off,' Nishinozu began explaining as they walked through the shell exhibit in the passageway connecting the new hall, 'Perhaps people mistakenly thought the aquarium would not reopen, so many locals called, saying it would be a shame and urging us to resume operations. We then pressured the police to allow us to open today.' He gazed upon the bustle of the new hall. Perhaps due to dealing with the incident, his face was more haggard than two days ago, with uneven stubble, yet pride beamed in his expression. The local residents who gathered, spanning various age groups, were they drawn out of curiosity from the news, or for other reasons? In front of the tank that was empty yesterday, now many people have gathered, not any less than when the lemon shark was still there. The tank was bathed in natural light coming through the skylight, and the adorable white dolphin, Luffy, was swimming gracefully. It seemed to have been moved here from the pool yesterday. Sometimes it waved its fin like a hand, eliciting applause, other times ignoring the cameras pointed at it, swimming away, bringing laughter. Yokohama Marumi Aquarium. A small-scale aquarium built at one end of Yokohama port. Sparse in highlights, struggling in operation, you won't even find the "Maru" character on Yokohama's guide map. Yet, everyone has visited at least once; it has deeply rooted itself in the citizens' memories. That's the kind of aquarium it is. 'Underestimate it not, Marumi far exceeds expectations.' Kaori softly recited a promotional line out of nowhere. The performance seemed about to start, with people continuously filling the seating area around the performance pool. They went around to the rear preparation pool to reunite with Teeko, who was swimming. As with yesterday, Shibaura was seen by the pool. However, strangely, even Tsutsu was leaning against the wall there. 'Cute, cute, so cute...' Seeing Teeko alive for the first time, Kaori's reaction was identical to Yuzuno's. She hurriedly clicked away with her camera. The clouds just dispersed, the temperature started to rise, and Risome, like yesterday, said, 'It's really hot.' 'Yo, a detective? Today you're accompanied by two girls?' 'I told you, that's not what's happening.' Yuzuno denied it by habit and asked, 'The show is about to start, isn't it?' 'Yes, you can watch. However, I'm obviously not going on stage. It's...' Shibaura nodded towards the door labeled "Waiting Room." Takino, wearing a red diving suit, happened to come out. 'Sorry, Mr. Shibaura, for troubling you again today.' 'No problem, no problem, it's just a small trouble... By the way, will you be alright on your own?' 'Yes. I have to show Amamiya-senpai that I can manage. And... I'm not alone, I'm with Teeko.' Takino glanced at her carefree partner slicing through the waves. Although this black dolphin supposedly couldn't hear her, it still let out a 'Chirp—' sound. 'Right, if anything happens, we're right here.' Izumi patted her chest. The intern Oiso and the part-timer Nishikawa came down the stairs and reported concisely, 'The sound system's fine.' Mizuhara appeared behind Yuzuno and others, giving Takino a thumbs up and said, 'As promised, I decorated it on the stage.' 'Sorry for the trouble...' 'No worries, no worries. Do your best then... Wait, Tsutsu, you're here, hurry back to work!' 'I'll go back right after the performance.' 'There he goes again...' The performance originally paired with Amamiya and Takino was now solely managed by the junior. The staff mobilized for its success. Kaori was excited, holding Takino's hand, promising, 'I'll definitely have it featured in the paper! Do your best!' Finally, the director glanced at his watch and murmured, 'It's almost time.' 'Did you see the audience seats? They're all full! Everyone’s supporting you, do your best!' '...Okay.' Takino nodded, summoned Teeko with a dog whistle, and headed towards the main performance pool. The audience was bustling, their cheers layered one over another. At the moment Yuzuno passed through the main entrance, she also noticed someone saying 'Do your best' to her alone. It was the taciturn, short-haired intern Oiso standing by the door. Takino responded with 'Uh-huh,' her face slightly flushed like yesterday. During that instant of encouragement, Oiso held Takino's hand, then immediately withdrew. The door recessed inward, creating a blind spot from the sides. It was an exchange only visible to those standing at the edges like Yuzuno and her peers. '...Did you see that, Risome?' 'Huh? What?' 'Oiso and Takino held hands... Takino's real boyfriend is Oiso!' 'Oh, is that so? Well, they are close in age.' 'Is that it... Can't you be a little more surprised? You really can't tell. Oiso himself says he's seriously reserved.' 'I don't think he's as reserved as he claims.' Risome said, looking at Oiso. He watched Teeko swim towards the performance pool and then returned inside expressionlessly. 'Truly serious and reserved people wouldn’t say that about themselves.' '...Is that so?' 'You two, hurry, it's about to start!' Kaori, already poised with her camera ready for action, called out to them. Izumi, Nishinozu, Tsutsu, and others were also heading to the front. Risome began to sluggishly step along the wall's shaded side. 'The aquarium sure is a mysterious place.' He watched the staff's backs, suddenly uttering such an inexplicable sentence. The performance pool was a semicircular pool surrounded by audience seats. The water surface was about one meter above the ground, with an acrylic section allowing viewing into the water. In the center of this semicircle stood the trainer's stage. The surrounding walls were designed to be undulating like the sea waves, harmonizing with the real sea and sky behind, creating an integrated blue world. Only the area above the audience seats had a roof, with sunlight dancing on the pool. The weather forecast was accurate, as the temperature indeed felt like midsummer. About three hundred spectators filled the audience seats to the brim. Although called seats, they were just long strips of plastic benches. People found spots to sit as they liked. There were high school students around Yuzuno's age, couples sitting shoulder to shoulder, and elderly couples holding guidebooks and chatting warmly. The most conspicuous were the family visitors. A little boy about three years old discovered the shop behind the seats, pestering his parents to buy popcorn, while an even younger baby suddenly cried in the mother's arms. On the seats by the edge, there was even an enthusiast male quietly setting up his camera. Yuzuno saw Izumi and Shibaura standing by the pool too, seemingly ready for emergencies. Light music flowed from the speakers. As soon as Takino appeared on stage, she was greeted with applause from the audience. Yuzuno and others managed to find a spot at the back to squeeze in. 'Hello, everyone! Thank you for coming to Yokohama Marumi Aquarium today!' Takino's voice rang out. She wore a headset, with a little pouch containing feed hanging around her waist. On one end of the stage was a bucket and a yellow ball, while the other end had an easel with a flat board on it. That was the photo of yesterday's Amamiya. In the end, it was placed in the most prominent position. 'Now, let me introduce my partner who wants to play with everyone—Teeko!' After the opening remarks, a sharp dog whistle sounded. Teeko immediately appeared from the water, repeatedly leaping to greet the audience. The children's cheers grew even louder. 'Teeko came to Marumi four years ago, a female dolphin. She's very curious, large in size, and a very healthy child!' Along with Takino's commentary, Teeko performed a somersault close to the audience seats. Its large body, not inferior to the shark's, drew a circle in the air, splashing water upon hitting the water. The junior high school girls at the front were drenched like wet chickens, laughing heartily at one another. 'Wow, amazing! Amazing! Forget publishing the article, use both pages for photos!' Kaori exclaimed words unsuitable for a newspaper reporter, frenziedly snapping shots with her camera. Simultaneously, Risome furrowed over trivial matters, 'It's a female dolphin. Oh, in the original story, it also gave birth to a baby. No, that was an orca.' Yet sitting between the two, Yuzuno couldn't bother thinking about what to say to them, entirely engrossed in the trainer and dolphin's performance. Teeko showcased its talents one after another to the rhythmically perfect accompaniment music. It ran as if it were on the water's surface, jumping continuously before diving into the water, then sprang to a height of about four meters. It balanced a ball thrown into the pool on its snout, then kicked it back to the stage with its tail fin. Its backstroke and adorable calls enchanted the audience. Takino exaggeratedly gestured, making the dolphin's lifestyles easy for children to understand. '—Next, we're going to challenge some more difficult techniques. This is also my debut performance for everyone. Teeko and I look forward to your support!' She announced as the performance entered the middle stage. Watching from the side, Izumi appeared surprised. Perhaps her actions deviated from the plan. Takino blew the dog whistle to her partner and also entered the water. The spectators watched this moment closely. Teeko traversed a large circle in the pool to her side, dove deeply—seemingly preparing to lift her on its back— Wow! Suddenly, the performance pool resounded with the loudest cheers of the day. Teeko swiftly swam with Takino on its back. Izumi swung her strong arms clapping heartily, rallying a round of audience applause. Takino, donned in the red diving suit, raised her arms in joy, smiling broadly. It's the same technique as in Amamiya's photo. 'The atmosphere is really lively!' Yuzuno heard a voice she heard every day at home from behind her. Her brother and Sendou were standing, watching the performance. 'Oh, even detective-san is here for the performance, so leisurely.' 'Aren’t you the same? You're supposed to be investigating, but are having fun instead… I heard this performance would be a tribute to Amamiya, so we came to take a look.' 'The photo's up there too.' Sendou glanced at the photo pointed out by Risome on stage, frowning, 'Really incomprehensible.' 'I understand how you feel. But everything here revolves around the creatures.' Their conversations were baffling. Yuzuno and her brother looked at each other blankly, tilting their heads. Kaori was the only one entirely ignoring everything around, continuing to press the shutter. Whether the storage card had enough space or not was unknown. Teeko returned its partner to the stage, swallowed the feed, and dived underwater again. Well-executing a high-difficulty move, Takino let her spirit relax and seemed a bit breathless. To her junior who completed the challenging task, the smiling photo of Amamiya seemed to mock her, 'You're still far from it.' Suddenly, Yuzuno thought—this smile resembled someone. A sleek and compact figure. Self-assured smile. Aloof character. Not long ago, she had fought against such a girl. '...Rain Palace somehow resembles Shinjiritsu a bit.' 'Don’t mention her now!' Risome instantly reacted to her murmur, 'At a time like this'—could it be he is also quite happy? 'However, I do feel they resemble each other somewhat. This composure.' 'Composure... Is she still unchanged?' 'Still unchanged?' 'I mean her queenly demeanor.' 'Oh... Yeah, kind of has that feel...' Perhaps it was break time, Takino let Teeko swim freely and started introducing the language of dolphins. While listening, Yuzuno began recounting the practice match's episodes to Risome. Shinichiritsu specially traveled from Kyoto to challenge Captain Sagawa. Garnering admiration from juniors and possessing devilish skills. Despite that, she sometimes slacked, at times arrogantly timed her moves, showing an extremely condescending attitude. Yet, Yuzuno thought she acted that way deliberately to provoke Captain Sagawa. 'She’s just a jerk.' 'N-no, not to that extent... Aren't you in a poor position to talk about others, Risome-kun?' No— 'Do you know Shinichiritsu well? What connection do you have with her?' '...' Yuzuno brought up the question again from two days ago. However, he didn’t answer, ignoring Yuzuno and started fiddling with his phone. Such a clumsy way to dodge a question. Could they have been a couple...? Over at the stage, Teeko once more exhibited its jumps, earning another round of applause. The brother behind her casually shouted, 'Hah!' Yuzuno clapped for Teeko too, but a knot remained in her heart. Right at that moment. '...Wait a moment!' Risome stood up. Because he was in the last row, no one noticed. Takino didn't either, continuing the performance with Teeko. Only Yuzuno, sitting close to him, noticed— The black pupils deep within his wide-open eyes. '...Risome-kun?' 'Wait! Wait! Wait...' Amidst the thunderous cheers, he silently pondered. His gaze fixed on Amamiya's picture. Her brother and Sendou were watching with surprise as Risome continued, 'Yeah... yeah... so, in other words… No, there's no evidence… No, wait… wait…' 'Risome, what's wrong with you?' 'Tenma? Hey, Tenma?' 'I say, Risome? For now just sit down, you're too conspicuous.' 'It's the mop.' 'Huh?' 'It's a mop!' Yuzuno's efforts were completely in vain, this shout drew all spectators' attention towards him. Takino was also taken aback, and Izumi, the director, and others froze. Even Teeko missed the ball tossed its way, just about to attempt a kick-related challenge. The sudden shout was followed by an awkward silence. However, Risome seemed utterly unconcerned, saying, 'Three people… no, two more people.' Then hurriedly dashed out of the seat. 'Hey, hey! Risome!' Yuzuno and Kaori scrambled to chase after him. The detectives followed too, along with Chief Sendou's angry bellow, 'What on earth is this guy doing?!' After exiting the performance pool, Risome sprinted across the new hall, towards Building A. Coral reefs, tropical fish, sea horses, and the white silhouette of Luffy, one after another flashed past their line of sight as they ran. With nearly all tourists gathered at the performance pool, the inside was quiet, regaining the deep blue ocean atmosphere. Passing through the dim space, Yuzuno and others hurried along while Risome efficiently searched for something from beginning to end. 'Mr. Oiso!' Just as they returned near the entrance, he finally spotted the person he had been looking for and stopped. This youth, having displayed unexpected sides at the pool, was now with Daitabashi, passing by in front of a large tank, today's buckets still in their right hands. '...What's the matter?' 'Uh? You came again today? Jeez, causing more trouble when we're already busy...' 'I have, one, request.' Risome ignored Daitabashi's grouch, speaking only to Oiso. Lacking stamina and after running such a stretch, he clutched his chest, as if just about to collapse."
Yuzuno caught up to him and said, "Is everything okay?" He simply raised a hand, indicating he was fine.

"A request?"

"Yes—shake hands with me."

Risome said this and directed the hand he had extended towards Yuzuno, turning it instead towards Kai Oiso. Oiso looked completely baffled, but he still extended the hand that wasn't holding a water bucket.

Risome's slender arm connected with Oiso's, which was more than twice its size and muscular.

"Thank you. Please keep up the good work. Give her my regards."

After shaking hands, Risome promptly sent the two of them away. Oiso blushed up to his ears, while Daitabashi pursed his lips and remarked, "I really don’t get it," as he headed towards the depths of the corridor.

Yuzuno and the others didn’t understand either.

"…Did that handshake have any special significance?" Sendou asked, with the fish in the large tank as the backdrop.

"Of course. Didn’t you see? His face turned red, didn’t it? Now he’s become a carrot."

"Huh?"

"I’m just joking. No problem, it was meaningful. It held great significance," Risome said with a satisfied look.

"Well then, I need to go back to my room because I have to install the air conditioning. Brother, can you call that person named Hatori for me again?"

"What?"

"Besides that, there are a few other things I need your help with. Ah, these are things Mr. Azusa can handle too; we’ll talk about it later... Hmm, what time does the aquarium close? Kaori, do you know?"

"Five o'clock."

"Alright, let's meet at five-thirty. Detective, please make sure to gather everyone. Oh, and by the way, contact the newspaper club guys as well…"

"Hey, wait a minute!"

This time, it was Yuzuno who extended her hand.

"Judging by this atmosphere, it seems you already know who the culprit is. You don't really…"

"I know!"

"What did you say?" Chief Detective Sendou shouted, stepping to Risome's side, "Re-re-really? You're not going to say you were lying again, are you?"

"No, it's true. Before, it was all hypothesis, but this time it’s completely based on facts; there’s no mistake."

"Enough with the nonsense. Quick, tell us who did it."

"As I said, I already know, so there's no need to rush! Anyway, I need to head back to my room now, and I also have to change into my school uniform."

"School uniform…?"

"Yes, you saw the performance just now, didn't you? For something like this, it must be aesthetically pleasing."

Risome shrugged off Sendou’s hand from his shoulder and strolled leisurely towards the entrance.

"W-wait! How do you know who the culprit is?"

Turning back in response to his brother's question, Risome’s smile, lit by the dim lights of the tank, was full of mystery.

"It's the mop, Brother. It's the mop, the bucket, and a few other clues… and the classic logic puzzle."