The next morning, Koro-sensei stood in the staff room clutching the roll book, his tentacles curled with cheerful energy.
"What a good start to the second term! The relationship of trust I share with my students is growing stronger every day."
He walked toward the classroom, already imagining the warm reception waiting for him.
"Today, too, they'll gaze upon me with such affection—"
He opened the door.
Every single student turned to look at him with pure, undisguised disgust.
Koro-sensei reeled back.
"Such disgust!!"
Without a word, several students held up a magazine. The headlines were impossible to miss:
Exclusive! Late-Night Terror in Kunugigaoka
Underwear Thief On the Loose!
Underwear Thief Strikes Again!
Only After F-Cups and Above
A Yellow Man's "Nuruhuhuhu" Echoing Through the Night
Okano's voice was flat.
"This is totally you, isn't it?"
Mimura crossed his arms.
"Honestly, we're disappointed."
Kataoka's eyes were cold.
"How could you do such a thing?"
Koro-sensei's tentacles flailed.
"No, wait! I don't know anything about this!"
Hayami stepped forward.
"So what's your alibi?"
Koro-sensei looked at her.
"My alibi?"
Hayami explained.
"Where were you late at night on the day of this incident, and what were you doing?"
Koro-sensei thought hard for a moment.
"…What was I doing? I was moving between ten thousand and three thousand meters altitude, shaking a bag of seasoned fries."
Maehara raised an eyebrow.
"Like anyone can prove that."
Akira raised a hand from his seat.
"Actually, I can. I was there too."
The entire class turned to stare at him.
Karma leaned forward.
"What were you even doing up there?"
Akira answered as if it were the most natural thing in the world.
"I was curious about the Mach 20 seasoned fries, so I tagged along."
Erika's head snapped toward him.
"Wait—that's what you were doing back then? Didn't you say it was something really, really important?"
Akira nodded seriously.
"It was important. Where else can I find out how Mach 20 shaken fries taste? I was scientifically curious."
No one knew what to say for a second.
Karma recovered first.
"…So is it good?"
Akira tilted his head slightly.
"Well… it became well-seasoned mashed potatoes. But other than that, it's good."
Hayami glanced back at Koro-sensei.
"So he has an alibi, then."
Kataoka still looked unconvinced.
"There's one for that night, sure. But we can't be sure about the other times, right?"
Isogai sighed and stepped forward, his expression serious.
"C'mon, that's enough. Koro-sensei may be full of the little desires of the flesh, but all he's really done so far is… read discarded dirty magazines, get bought off with swimsuit pics, stare intently at pin-ups during free period, send in postcards saying 'Hand-bras are so blah! Let me do a tentacle-bra!'…"
His voice lowered toward the end, and he turned away from Koro-sensei.
"Sensei… just turn yourself in."
Koro-sensei's face twisted in betrayal.
"Et tu, Isogai-kun?!"
He flailed his tentacles wildly.
"How rude! I'm an innocent man! If you don't believe me, come to the staff room! I've got just the thing to prove how rational I am!"
The class followed him.
Koro-sensei threw open his desk drawer with dramatic confidence.
"The pin-up collection in my desk! I'll get rid of every last one of—"
As he started throwing his magazines, his tentacle froze halfway through the motion.
What he picked up was a purple bra.
The room went dead silent.
Terasaka's voice was flat.
"…You're kiddin' me."
Okano walked in holding the class roll book and held it up for everyone to see.
"Hey, everyone, check out the class roll book. See the letters next to all the girls' names? He's done research into all our cup sizes!"
Kayano's eyes locked onto her own name. A second later, she let out a devastated scream.
"Hey! Why am I the only one marked 'forever flat'?!"
Maehara picked up another sheet from the desk and unfolded it.
"And this here—'Kunugigaoka's F-Cup and Above.' A list of the women in Kunugigaoka with at least an F-cup!"
Koro-sensei was visibly sweating now.
"Wait! I… that can't…!"
The collective look of disgust only deepened.
In a last desperate move, he grabbed a cooler box from under the desk.
"Oh, right! I was getting ready for an after-school barbecue!"
He flipped the lid open and pulled out a set of skewers with forced cheer.
"See? Don't these skewers look delici—"
There was no meat on them.
Only bras of different colors, neatly pierced and ready for grilling.
For a long moment, no one said anything at all.
---
The rest of the day's classes passed in awkward silence.
When the final bell finally rang, Koro-sensei floated toward the door with none of his usual energy.
"T-That's all for today… class…"
He staggered out into the hallway.
"…Then see you… tomorrow…"
The moment the door closed, Karma leaned back in his chair and laughed.
"We really put him through the wringer today, huh? Guess he couldn't stand the heat."
Nagisa frowned slightly.
"But did Koro-sensei really do it? I mean… it's a serious crime."
Karma shrugged.
"Compared to blowing up the Earth, it's downright adorable."
Nagisa nodded.
"…Yeah, well…"
Karma picked up a ball from under a desk. A bra was tied around it.
"But if I were a Mach 20 underwear thief, I sure wouldn't leave such shoddy evidence behind."
He tossed the ball lightly toward Nagisa.
"A ball from the equipment shed. He'd have to know that if he did this, he'd be dead to us as a teacher. For that teaching-mad monster, losing our trust with this nonsense is right up there with getting assassinated in terms of things he wants to avoid."
Nagisa caught the ball and looked at it for a moment.
"…Yeah. I'd have to agree."
Akira stood up and raised his phone.
"Everyone, look at this."
A large satellite map of Kunugigaoka projected onto the classroom wall.
Nagisa blinked.
"Is that a map of Kunugigaoka?"
Akira nodded.
"Yes. But look at this."
Multiple red lines appeared across the map, tracing rapid paths through the area.
Karma's eyes sharpened.
"What are those lines?"
"These are supersonic disturbances," Akira explained. "This particular satellite picks up objects moving faster than sound. Usually they indicate jet aircraft, but in Kunugigaoka, it's only Koro-sensei. This shows every place he's been in the last seven days."
Karma immediately caught on.
"Ohh. With this, we can see exactly where Koro-sensei has been."
Akira nodded.
Maehara raised both hands.
"Wait, wait, wait—how did you even get a satellite?"
Fuwa leaned forward, eyes wide.
"Yeah, how did you pull a Batman here? Do you own a satellite?"
Akira looked away.
"…That I cannot answer."
Fuwa stared at him.
"Isn't that basically admitting it? But how did you even get it up there?"
Akira cleared his throat and quickly moved on.
"Anyway. From Koro-sensei's path over the last week, and based on the accounts of the victims I personally checked, he wasn't moving at his usual speed during the incidents. When you compare all their locations with every woman in Kunugigaoka who has at least an F-cup… Koro-sensei was nowhere near them."
Erika's hand shot out and grabbed his shoulder.
"How did you know where all the F-cup women in Kunugigaoka live? When did you talk to them?"
Akira's face went pale.
"Wait—I am innocent! I just messaged them online… I am innocent!"
Kayano ignored his struggle and looked around the room.
"If it's not Koro-sensei, then… who?"
Fuwa stood up so fast her chair scraped against the floor.
"An imposter."
Kayano blinked.
"Fuwa?"
Fuwa's eyes were shining with excitement.
"That color, his laugh… Make no mistake. It's a fake sensei! The old hero-movie bad-guy trope in action!"
She pointed dramatically at Ritsu's screen.
"So the culprit is someone deeply familiar with Koro-sensei. Ritsu! Look for clues with me!"
Ritsu's display immediately switched to a detective-style interface.
"Sure!"
Karma crossed his arms, still smiling.
"Something along those lines, anyway. I don't know why they'd do something like this, but if this rumor drives our bountied buddy out of town, we'll lose everything. Let's beat the real criminal silly and put that octopus in our debt."
The class answered in unison.
"Yeah!"
Meanwhile, off to the side, Akira was still being pinched by Erika, leaning away from her with tears in his eyes.
"I am innocent—!"
---
By nightfall, a small team—Akira, Erika, Fuwa, Nagisa, Karma, Terasaka, and Kayano—vaulted over the wall of a quiet building compound and dropped into a crouch behind a parked car.
Fuwa adjusted her imaginary detective hat with complete seriousness.
"A great detective, practically grown up in both body and mind, has arrived."
Nagisa gave her a flat look.
"All we're doing is using parkour to trespass."
Terasaka scratched his head.
"Hey, Fuwa. How do you know the culprit's gonna strike here next?"
Fuwa held up a finger.
"This is a training camp for a certain professional idol group. They've been here for two weeks practicing their latest dance routines."
Akira added helpfully,
"And all of them are above F-cup."
Erika immediately pinched his cheek.
"How did you know that? Do you watch them?"
"No—!" Akira winced. "I just checked. It's on their wiki!"
Ritsu, in her detective outfit, appeared on Akira's phone.
"Based on the suspect's disposition, there's a 99.78 percent probability this place is in his sights."
Fuwa nodded firmly.
"And tomorrow's the last day of camp. No way will our man let these top-notch trophies get away."
Terasaka grunted.
"…I see."
The group moved quietly to the backyard, where rows of laundry hung on drying lines, and settled into position to wait.
For a while, nothing happened.
Then they spotted a familiar yellow shape dressed entirely in black, crouched in the bushes and also staring intently at the laundry.
Nagisa whispered,
"Koro-sensei? Is he after the real thief too?"
Terasaka snorted.
"Sure looks like a thief in that getup."
Fuwa leaned forward, eyes sparkling.
"Look! He's so mad at the actual culprit, he's looking at the underwear and getting all worked up!"
Terasaka shook his head.
"I can't see him as anything but the bad guy!"
Karma suddenly pointed.
"Hey. Over there…"
A figure in a yellow helmet and a crude Koro-sensei-like outfit sprinted out of the shadows. With practiced, efficient movements, he yanked every bra from the drying lines, stuffed them into a bag, and turned to run.
Kayano's eyes widened.
"Oh no—he's getting away!"
Before any of the students could move, the real Koro-sensei exploded out of the bushes and slammed the imposter into the ground.
"Got you!" Koro-sensei declared, tentacles pinning the man down. "So you disguised yourself as me and did things I only wish I could have done! I'll strip you naked and take care of you from stem to stern! Nuruhuhuhuhu!"
Nagisa's face went pale.
"…This may be even worse than being a bra thief."
Karma smirked.
"The reports got his laugh exactly right."
Koro-sensei yanked the yellow helmet off the man's head and froze.
"…You are…"
Kayano squinted.
"Isn't that… one of Karasuma-sensei's subordinates?"
Koro-sensei's voice dropped.
"But why did you—"
The ground beneath them clicked.
In an instant, tall white sheets shot upward on all four sides, forming a tight cage around Koro-sensei. The moment one of his tentacles brushed the fabric, the tip sizzled and melted.
Shiro walked into the courtyard with slow, deliberate steps, his hands folded behind his back.
"I negotiated with the government to borrow one of Mr. Karasuma's men. He lured you right into this pen of anti-sensei sheets."
The subordinate scrambled out from beneath the sheets and fled. Koro-sensei tried to pursue, but every contact with the white cloth burned his tentacles further.
Shiro continued, almost conversationally.
"It's what your students did on that southern island. Youngsters have such limber minds. First confine… then strike."
He raised one hand and snapped his fingers.
"Now, Koro-sensei. Let your final death match begin."
From the rooftop above the pen, a figure dropped straight down, landing lightly inside the cage.
Itona straightened, tentacles already unfurling, anti-sensei blades gleaming along their lengths.
"Koro-sensei… compared to me, you are… weak…"