There's a saying—
the twenty-first century belongs to information technology.
And at least for now, that seems undeniably true.
Reflecting that brilliance, within St. Eden Academy, the IT Club holds the highest status among all student organizations.
Not only do they command the largest share of the school's three-billion-yen annual activity budget, but they also occupy the entire top floor of the Academy's massive club building.
Yet outside the IT Club itself, very few students ever bother to climb those final stairs to the top.
Because, quite frankly, the environment up there is… terrible.
For their activities, the IT Club had converted several rooms into server rooms.
Just stepping onto the staircase leading to the top floor was enough for the deep, grinding hum of machinery to vibrate through the walls and ceiling—
a low, unsettling resonance that made it feel like even your bones were rattling.
And to keep their servers from overheating, industrial-strength air conditioning ran day and night throughout the year. The entire floor exhaled a freezing, sterile chill.
Now that it was already November, there were very few who could stand such icy air—
apart from the members of the IT Club, who had long since grown used to it.
That was precisely why, when Teacher Zeshiro climbed the stairs toward the top floor and unexpectedly spotted a boy and a girl standing at the landing, she nearly jumped in fright.
"Hara Kei… and Yukinoshita-san?" She blinked in recognition.
They were two of the members of the Lambs' Circle she had met just this afternoon.
"What are you two doing here?"
Especially Hara Kei—among the sea of female students, his presence as the "one spot of green among all the blossoms" had left quite an impression on her.
Yukinoshita Yukino didn't say a word.
To identify the culprit—to reason, to accuse—
that was the privilege of the victor.
Unfortunately, she was not the victor this time.
So she stayed silent, those deep obsidian eyes quietly turning toward the boy beside her.
After school, she had immediately left her Class 1-B and run to the doorway of Class 1-A.
When she arrived, she found Hara Kei already waiting there for her.
He didn't look surprised to see her—just gestured lightly for her to follow.
Tch, acting all smug just because you figured it out before I did.
Yukinoshita muttered inwardly but followed nonetheless.
She had already guessed who the culprit was, but she had no idea how to prove it—no evidence, no motive, no location.
In those aspects, she had indeed lost.
Well, Yukino… it seems you've found quite an interesting person, she thought with a faint, self-deprecating smile, hurrying after him.
Her agile movements hardly matched her image as a "sickly girl."
"We're here, of course, about the request you gave us earlier today, Teacher Zeshiro," Hara Kei said as he stepped forward.
His tone was calm, yet the quiet confidence radiating from him made the teacher instinctively shrink back.
But she quickly forced herself to compose her expression, squeezing out a nervous smile.
"R-Really? I didn't think the Lambs' Circle would solve it so quickly! So, who was it?"
As soon as she asked, she noticed both students looking at her with strange expressions—
and her heart skipped a beat.
"The culprit," Hara Kei said evenly, "is you, Teacher Zeshiro."
Yes—whether it was the stolen swimsuit or the so-called pool ghost, the entire incident had been orchestrated by none other than Teacher Zeshiro herself.
"When I went to the pool at noon," Hara Kei began, "I tested the water temperature. It was around fifteen degrees Celsius. That's way too warm for an unused pool."
"If the girls' swim club is really struggling financially, as you said, why would anyone waste electricity heating the pool at noon—when no one's even using it?"
"Unless," he continued, "the person who turned on the heater knew that someone would be jumping into that pool very soon."
He paused, his expression turning thoughtful.
"Normally, you'd only start heating the water before the final class of the day, so that the temperature would be perfect for after-school practice."
"…So you started suspecting me from that point?" the teacher asked quietly.
"Not exactly," Hara Kei replied with a sigh.
"The real hint came when I saw you open the pool doors yourself—with your own key."
"You remember, right? You took that phone call in front of us before heading there."
"But the person who called you—shouldn't she have been waiting inside the pool room for us? So why were you the one opening the door?"
That sharp, soul-piercing question silenced her completely.
She had once joked that she wasn't very bright—
but now, it seemed that might not have been a joke at all.
Watching her droop in defeat, Yukinoshita finally spoke up.
"Then… what was the point of all this, Teacher Zeshiro?"
Stealing the spare swimsuits from storage and scattering them across the pool's surface…
Sticking black fabric tape along the bottom of the pool…
Then reporting it all as a mysterious incident to the club…
What on earth was she trying to achieve?
That was the one part Yukinoshita truly couldn't comprehend.
"The traps themselves weren't the point," Hara Kei said.
"What mattered was what the Lambs' Circle did after that."
"…What we did?"
"Yes. That's where her real goal lay."
And then Yukinoshita realized.
"Ah—!"
She recalled what Chika Fujiwara and Kaguya Shinomiya had done afterward—
changing into swimsuits for the investigation.
So that was the real purpose.
"Recently," Hara Kei continued, "our school's online forum posted a new mobile game uploaded by the president of the IT Club. It's still in beta."
"The post also asked for bug reports and suggestions… and student photos."
"Uniform photos don't sell for much. Casual wear goes for double. And above that—miko outfits, bunny suits, swimsuits, lingerie…"
He exhaled through his nose.
"When I checked the game's character illustrations again this afternoon, I noticed something. Those sprites weren't drawn by an artist at all—they were generated from a 3D-to-anime image converter. That's how the IT Club's president can push into the mobile game scene with such confidence."
"After all, with that technology, their illustration costs are practically zero."
Akasaka Ryūnosuke really was a genius. To think he'd go this far…
Unfortunately—
"The girls' swim club was in serious financial trouble," Hara Kei said coldly.
"As their advisor, Teacher Zeshiro had no choice—or so she thought. So she decided to trade swimsuit photos in exchange for funds to keep the club afloat through the winter."
"I don't know how deep the club's deficit runs," he went on, his eyes narrowing.
"But no matter how desperate you were, deceiving others and exploiting their goodwill for money is unforgivable."
"Someone like that…" His voice sharpened.
"…isn't fit to be called a teacher."