The rat hunt in U.A. officially began thanks to Tsutsumi kick-starting the entire operation. With his push, Nezu and the U.A. staff immediately coordinated with the police and moved the investigation forward.
The first step was the simplest: check every staff member, faculty, and the Wild Wild Pussycats.
After a very long round of questions and lie-checks, the result came back clear, none of them had shared anything about the Summer Camp with anyone who wasn't supposed to know.
That part made Nezu smile. At the very least, none of his teachers or pro hero partners were the mole.
The next part made that smile vanish.
The remaining suspects were the students of Class 1-A and 1-B.
Even though Tsutsumi was already considered "cleared" due to being the one who started this whole operation, he still agreed to sit down and give his statement. His only complaint was making sure no one could later scream, "This is all Decade's fault!"
Nezu laughed at that, at least until he reviewed the surveillance footage and saw how many of Tsutsumi's classmates blamed him for their failed final exam.
At that point Nezu stopped finding it funny.
Yes, Tsutsumi's existence raised the exam difficulty. But students like Bakugo and Todoroki still managed to overcome those odds and pass. Blaming Tsutsumi for failing an exam you personally couldn't clear was, in Nezu's eyes, a special brand of nonsense.
In the end, Tsutsumi was marked "clean." The investigation continued through the rest of both classes.
Eventually, everything narrowed down to a single name.
"Aoyama Yuga…" Nezu murmured, reading the report Detective Tsukauchi handed him.
Plenty of students had told their parents and friends that they were going to a U.A. Summer Camp. But none of them had given away details beyond "training" and "school trip." Nothing serious.
Aoyama's case was different.
When Detective Tsukauchi questioned him, the boy got visibly nervous, then lied right to the detective's face. Even when Tsukauchi shifted his phrasing or softened his tone, Aoyama kept lying. Lie after lie. Not one answer came back clean.
There was no helping it, they had to detain him for the time being. The police were also sent to secure his home and bring in his family.
Nezu took the entire matter extremely seriously. If this ever reached the public before they contained it, U.A. would be buried in backlash. But there was another reason he was tense:
Aoyama was a student of Class 1-A.
Meaning if this spiraled out of control, Tsutsumi would very likely be the one forced to deal with Aoyama directly.
People liked to call Tsutsumi an irresponsible Class President based on the paperwork records, but anyone who actually watched him outside those reports knew better. He took his responsibilities seriously, just not in the "by the book" way teachers were used to.
He helped his classmates improve, pointed out weaknesses they didn't see, and even developed training plans to match their personalities.
Aizawa could list several examples, but the clearest one was Jiro Kyoka.
When she first entered U.A., she only ranked 15th in Aizawa's initial assessment test, good enough, but nothing outstanding.
But with Tsutsumi's help, she'd risen far above that. Aizawa could now confidently say that among the girls of Class 1-A, Jiro stood at the top, and had closed enough distance to challenge the likes of Todoroki and Bakugo.
...
Three days went by without him even noticing. Tsutsumi was sprawled across the sofa, lazily turning the Cross-Z Dragon over in his hand. He slid the Dragon Fullbottle into the device, watching it glow before it reshaped itself into the Kamen Ride: Cross-Z card.
"Hmmm… three days already. Nezu has to have found something by now," he muttered, picking up his phone and firing off a short message.
[TsutsumiRyoko]: @Nezu You found who the rat is yet?
It didn't even take a full minute before replies started popping up.
[Nezu]: Don't worry, Tsutsumi-kun, this matter is already being handled.
[MaijimaHigari]: How did a student get into the teacher's chatgroup??
[AizawaShota]: @TsutsumiRyoko If you stay in here, you're working as a teaching assistant.
[TsutsumiRyoko has left the Chatgroup]
He shut the screen off. Tsutsumi was ready to toss his phone aside, but a notification from Miyu caught his eye. Opening it, he found several clear, well-framed pictures of her and the Jiros on vacation.
"This must be Mr. Kyotoku and Ms. Mika taking these. Definitely not Miyu…" Tsutsumi murmured.
He knew too well that Miyu and cameras didn't get along, similar to him; unless "distortion" suddenly became some new photography trend, then he could be said to be the best at taking them.
He saved every picture before getting up and heading to the study room.
Inside, he set down his camera, removed the film, and began developing the ones he took. At the same time, the printer beside him started humming to life, spitting out full-color prints of the photos Miyu sent.
Yaoyorozu's Quirk really was broken in the most convenient way possible. With it, he'd already made tons of stuff in his house.
And when his own Quirk reduced the cost and drawback of using other powers, then Azu's research piled on top of that… well, he could basically create almost anything he wanted.
It saved him more money than he expected. All of it, of course, was getting funneled straight into Miyu, her life, her future, everything she'd ever need. After all, she'd been his only family for years, and he had absolutely no intention of being stingy with her.
He had even considered taking her to the AR world, the one where Hoshimi Miyabi adopted him. But that place was… unstable, at best, and dangerous, at worst. If she didn't develop the immunity he did, he wasn't going to risk it. A fun trip wasn't worth losing her.
When the last picture finished printing, Tsutsumi finally turned toward the far end of the room, where the massive information board stood. Every photo, note, and thread he'd gathered about his missing mother, Tsutsumi Kaina, covered its surface.
Finding her had been his original goal when he applied to U.A. That was the entire reason he even stepped foot in this hero school.
But the glimpse of the future his older self had shown him… it changed things. It made him hesitate. For the first time, he wasn't sure if chasing after her was still the right path.
A part of him still wanted answers. Wanted to fill the hole she left behind. Wanted to understand.
But another part of him, the part that had a place to call home and a family, kept whispering that maybe he already had everything he'd been searching for.
"This sucks…" Tsutsumi muttered, long and exhausted. "It seems that the only person who can beat me up... Is still me."
He put the camera back on.
An Aurora Curtain shimmered into existence in front of him, familiar and welcoming. Without another word, Tsutsumi stepped through it.
...
In another world, Tsutsumi sat quietly at a small empty café table, eating an ice cream sundae as if he had absolutely nothing to do with the chaos unfolding above the skyline.
In the reflection of a nearby skyscraper, he could clearly see a massive red dragon-shaped monster flying across the glass.
"Rider War, huh…" Tsutsumi murmured, spoon still in his mouth. The setup reminded him of Ryuki's world, Riders thrown into an endless battle, and whoever survived got a wish.
Pretty much a mirror-themed Holy Grail War.
He paused.
Well… one Holy Grail War at a time. He already had the Fuyuki one on hold simply because he felt like it.
He watched another clash happen in the skyscraper's reflection. Blades, sparks, explosions, and absolutely nobody dying.
"Huh. They're all ganging up on Ryuki?" he said, lowering his spoon. Sure enough, all thirteen Riders had somehow decided to collectively bully the poor guy.
"Interesting…" Tsutsumi stood up, finished the last bite of his sundae, then walked toward an empty decorative mirror on the café wall. He pulled out his card.
"Henshin."
Form Ride: Decade!
Colored after-images swept around him as his casual outfit shifted neatly into Decade's clothes. Tsutsumi stepped forward, entering the Mirror World as if walking into a convenience store.
His sudden appearance, and his half-Rider form made every Rider freeze and turn toward him.
"So what's the deal? Ryuki too strong, so everyone decided to beat him up first?" Tsutsumi asked in a flat, casual tone.
"Oi oi… you shouldn't stick your nose into other people's business!" Scissors barked before rushing at him, crab claw raised.
Attack Ride: Slash!
Tsutsumi swung his blade instantly. Scissors was launched backward, scraped across the concrete, and rolled until he crashed into a railing. The other Riders stiffened.
Tsutsumi ignored them and turned toward Ryuki, who was curled on the ground and struggling to breathe.
"So what's going on?"
"P-Please… y-you must… stop this… meaningless war…" Ryuki managed, right before his body dissolved into particles. Leaving only his Advent Deck remained.
Tsutsumi blinked. "Huh. Didn't expect him to die that fast."
He picked up the Advent Deck as it transformed into a card.
Kamen Ride: Ryuki
The remaining Riders watched him carefully, trying to decide whether he was a threat or just some tourist.
A faint smirk appeared on his face. "Well, since this was Ryuki's dying wish, I don't mind handling it for him."
"Who do you think you are?" Odin demanded.
"Just a passing-through Rider," Tsutsumi replied simply, holding up the new card.
"Henshin."
Kamen Ride: Ryuki!
His appearance shifted into Ryuki's armor, well, half of it anyway, with only the eyemask of his face covered by the dragon-shaped mask.
Seeing an unfamiliar half-Ryuki, Gai, Ouja, and Tiger wasted no time, rushing him from three angles.
Tsutsumi drew the Dragsaber and met their blades head-on. Despite fighting three Riders at once, he held his ground better than the original Ryuki ever did. Even so, he kept one eye on the Riders keeping their distance and circling for a cheap shot.
Knight and Scissors soon rejoined the fight, followed by Raia and Femme. The battlefield turned into a chaotic mess of metal, sparks, and shouting, basically everyone versus the new guy.
"Just like old times…" Tsutsumi muttered, feeling oddly nostalgic. Everyone ganging up on him was practically a tradition at this point.
Form Ride: Primitive Dragon!
A ghostly cyan dragon skeleton rose behind him before coiling around his body, its claws locking over his torso like armor. A pale, spectral hue washed over his crimson coat.
"So it really works…" Tsutsumi said, glancing at his left hand while the skeletal claw effortlessly lifted Knight by the neck.
He had always suspected his additional forms could stack, like when he mixed Black Hazard with Aizawa's Quirk, or combined Pyrrha with Sparkling Form.
But this was the first time he mixed a Rider's main form with a completely different Rider's additional power.
Kamen Rider Ryuki: Primitive Dragon.
Definitely not canon… but it worked.
"Sorry for keeping you waiting," he said, right as the dragon claw snapped Knight's neck and dropped the body, which dissolved into another Rider Card.
He pointed his blade at the remaining Riders.
"But I'm ending this war right here… right now."
The other Riders immediately turned and ran. Smart decision, given the sudden spike in danger from an unknown threat.
Final Attack Ride: S-S-S-Saber!
The dragon claw detached itself, shooting forward and slamming into the massive mirror the Riders used as their only exit. The entire surface shattered instantly, glass raining across the Mirror World. Now they were trapped inside.
The other Riders, if they want to travel between the Real World and the Mirror World, can only use the same mirror that they traveled in.
Tsutsumi, however, wasn't bound to any single portal. With his freedom to pass through any reflection, he was the only one who could come and go as he pleased.
The sound of falling shards mixed with his calm footsteps as he approached the panicked Riders.
"As I said, I'm ending this meaningless war."
His figure reflected over and over in the broken mirror shards right before they hit the ground and shattered again, until the only thing left was the echo of his steps.