“I can’t believe this.”

Yu Takeyama’s voice, muffled by the rim of her coffee mug, cut through the Sunday morning silence. She was sunk into a corner of the sofa, with a pile of papers on the coffee table.

“I swear, being a pro hero is more about filling out reports on dented streetlights than actually being a hero.”

Across the room, at the small kitchen table, Izuku looked up from his bowl of cereal. His brow was slightly furrowed, his spoon halfway to his mouth.

“You’re approaching the problem inefficiently.”

Yu shot him a look over her mug. “Excuse me?”

“The paperwork,” he said, setting down his spoon. He leaned forward, with a sudden intensity that clashed with the morning’s calm. “If you grouped the reports by damage type instead of by date, you could create templates. One for public property damage, another for collateral damage insurance claims, another for civilian injury reports…”

“Izuku,” she interrupted, her tone half warning, half amusement. “It’s Sunday morning. My brain refuses to process the word ‘template’ before noon.”

“But it would save you a lot of administrative work time,” he insisted, completely serious. “We could even develop a system of simple macros to autofill the recurring fields. Hero name, license number, agency…”

A small, genuine, and tired smile formed on Yu’s lips. “Thanks for the unsolicited advice, brainiac. I’ll add it to the list of things I’ll probably never do.”

“But it’s inefficient,” he muttered, returning to his bowl, though his gaze remained fixed on the pile of papers, analyzing it.

“It’s my way of rebelling against the system,” she replied, taking a sip of her coffee.

The silence that followed was comfortable. There was a strange normality in the air, a calm that had settled after the storm of the previous week. He was still her assistant, weird and socially awkward. The only constant in the madness that was her life.

She was about to make another sarcastic comment about efficiency when the peace of her morning was brutally interrupted.

BANG! BANG! BANG! BANG!

A thunderous, fast, and insistent rhythm echoed from the front door. The pounding made the mugs vibrate and Yu’s coffee spill onto her hand.

“Ow! What the hell…?”

Izuku was already on his feet. “Are you expecting someone?”

“No one who tries to knock the door down!” she hissed, heading cautiously to the entrance.

She looked through the peephole and a groan of pure annoyance escaped her. She opened the door just a crack, enough to peek her head out.

“What do you want, Mirko? It’s ten in the morning on a Sunday.”

On the other side, Rumi was smiling with overflowing energy. She wore a black sports top and gray compression leggings that fit her muscles perfectly. She didn’t wait for an invitation. She pushed the door open with the palm of her hand, forcing it wide and making Yu stumble backward.

“Good morning, lovebirds!” she announced, her voice echoing into every corner of the apartment. “I could smell good coffee from the hallway. I need fuel! You wouldn’t think of leaving your favorite training partner dehydrated, would you, Yu?”

Completely ignoring her host’s indignant expression, Mirko strode into the apartment, her eyes quickly scanning the place. Her gaze landed on Izuku, who was watching her from the kitchen, still on guard.

“Squirt!” she greeted him with a cheerful nod. “You look less pathetic when I’m not using you as a punching bag. Almost.”

She headed straight for the kitchen, walked past Izuku, opened Yu’s fridge without a hint of hesitation, and pulled out a bottle of cold water. She took a big gulp, leaned against the counter, and looked at them both with a chaotic energy that had already completely shattered the morning’s peace.

“So,” she said, wiping her mouth with the back of her hand. “I ran into Nemuri at the gym this morning. She was acting weird.”

Yu rolled her eyes as she closed the door. “Define ‘weird.’ For Nemuri, that’s a very broad spectrum.”

“She was… glowing,” Mirko continued, ignoring her. Her gaze locked onto Izuku. “She wouldn’t stop talking about ‘Quirk condensation’ and ‘qualitative potential.’ She sounded just like you when you go into nerd mode. So, spill it. What did you do to her?”

Izuku, who had been watching the invasion with a mixture of surprise, lit up at the question. He left his half eaten cereal on the table, excited to share his discoveries.

“It was an incredible success!” he said, approaching them, his social nervousness forgotten at the chance to talk about his research. “Midnight-san’s Quirk is fascinating. Her theory that my power could influence her Quirk’s manifestation, and not just her physical attributes, was correct.”

Mirko leaned forward, her interest now genuine and sharp. “Yeah, yeah, science. Get to the point. What exactly did you do?”

“It wasn’t just about making her stronger or faster,” Izuku explained, his hands moving as he spoke, gesturing to shape his ideas. “It was different. Midnight-san’s power usually manifests as a gas. It expands, fills an area, but its precise control is limited.”

He paused, searching for the right words. “What we achieved was changing its state. We condensed that gas into a liquid. It’s still her Quirk, with the same potency, but in a much more concentrated and controllable form.”

“The same substance, the same power, but in a completely different form,” Izuku continued, his enthusiasm growing with every word. “She was able to create a thread of her gas and move it at will with total precision! And then she condensed it into a liquid! She could administer it with a dart or a capsule! The tactical implications are enormous!”

Mirko’s mind, always focused on combat, processed the information instantly. Her eyes widened, her playful smirk disappearing to be replaced by an expression of intense concentration.

“Incredible,” she whispered. “You mean you can not only increase the power of someone’s Quirk, but you can change how it works?”

“That’s an excellent way to put it!” Izuku exclaimed, delighted that she understood so quickly. “Yes, exactly! It’s not about quantity, but quality.”

Mirko stared at him, her red eyes gleaming with a wild possibility. She pushed herself off the counter and took a step toward him, her presence filling the kitchen, closing the space between them.

“Do it to me,” she said, her voice a low, eager whisper.

Yu snorted from the living room. “Didn’t you have enough with nearly demolishing a training building last time?”

“That was speed,” Mirko replied, not taking her eyes off Izuku. She turned slightly toward him, her body already adopting an instinctive combat stance. “Can you make my kicks hit harder? Not faster, but with more… force. Can you change the type of impact? Instead of piercing, make it… crushing. So it smashes instead of going through.”

The question made Izuku’s brain race. It was a brilliant hypothesis, a direct and brutal application of what he had learned with Nemuri.

“That is… an excellent theory,” he murmured, his eyes unfocusing for a second as equations and possibilities ran through his mind. “It’s consistent with Nemuri’s experiment. If we can change the state from gaseous to liquid, we should be able to alter the inherent properties of the impact… the kinetic energy transfer could be reconfigured from a high, focused pressure point to a wider area of effect with superior concussive force…”

As his mind plunged into the labyrinth of theoretical Quirk physics, his eyes, almost by instinct, drifted. They left Mirko and landed on Yu, who had sat back down on the sofa and was watching them with her arms crossed and a look of profound exhaustion.

But Izuku’s gaze was different this time. It was the look Yu had come to fear and hate in recent weeks: that of a scientist who had just found the perfect specimen for his new and insane experiment.

And that look, intense, focused, and completely devoid of social awareness, was fixed, unblinking, on a very specific part of her anatomy.

Her butt.

The intensity of his stare made Yu feel an uncomfortable heat spread across her skin, rising from the back of her neck to her cheeks. She shifted on the sofa, pulling down the hem of her loose shirt.

“Izuku…” she said, her voice a clear warning.

He didn’t hear her. He was completely lost in his thoughts, his head tilted slightly.

“What do you think you’re looking at?” she asked.

Mirko, curious about the boy’s sudden silence, followed his line of sight. A slow, malicious, and absolutely devilish smile spread across her face. She leaned against the kitchen doorway, crossing her arms, clearly ready to enjoy the impending disaster.

“Careful, squirt, your eyes are gonna dry out from staring,” Mirko said, her voice dripping with amusement. “What’s so damn interesting? Did you discover the secret of the universe on Yu’s couch?”

Mirko’s question finally snapped Izuku out of his trance. He blinked a couple of times and looked at the two women. His expression showed no embarrassment for being caught, but rather the concentration of someone who had just had a scientific breakthrough and was ready to present his findings.

“I’m reevaluating my initial data,” he said, with absolute seriousness, as if he were at a science conference.

Yu groaned and covered her face with one hand. “Oh, no…”

“My first experiment with you, Yu,” he continued, completely oblivious to her suffering and gesturing vaguely in her direction. “Was an increase in ‘mass and firmness.’ It was a… quantitative result. I simply increased the properties that already existed. It was a success, but a simple success.”

He gestured toward the door, as if Nemuri were still there.

“But the experiment with Midnight-san was qualitative. We changed the fundamental property of her Quirk.”

His gaze, now filled with a new and terrible scientific curiosity, returned shamelessly to Yu’s butt. He pointed casually with his chin.

“I wonder what properties I could change there. The first touch was an accident. The intent was unfocused, the energy flow was a raw pulse. But now that I understand the mechanism better? Could I make it more… elastic? You could absorb the kinetic energy from an impact and return it. It would serve to propel you in jumps or to return an enemy’s blow.”

Yu’s face turned completely red. “Izuku, stop…”

He ignored her, lost in his own brainstorm. “Or could I make it denser? To give you such a low and stable center of gravity that not even All Might could move you. You’d be immovable! Or maybe I could alter the surface texture on a microscopic level to increase friction. You could stick to walls! The possibilities are…”

“STOP TALKING ABOUT MY BUTT LIKE IT’S A MIDDLE SCHOOL SCIENCE PROJECT!” Yu yelled, her voice echoing with a mixture of fury and pure humiliation.

Izuku sighed, a sound of genuine professional frustration, as if she didn’t understand the importance of his research. He completely ignored her outburst, lost in the methodological problems of his initial experiment.

“The problem,” he said, more to himself than to them, raising a hand to his chin. “Is that my first contact was an accident. The only clear note I have from that time, before I could understand the qualitative transfer mechanism, is that it was…”

He paused, searching his vast mental database for the most accurate description.

“…too comfortable.”

He stopped, frowning, visibly annoyed by this flaw in his own procedure.

“The comfort level was so unexpectedly high that it interfered with the collection of objective sensory data. The tactile feedback was overwhelming. It was a fundamental confounding variable in the experiment.”

The statement, so serious, so clinical, and so utterly ridiculous, hung in the uncomfortable silence.

Yu’s mouth fell open, the words of protest dying on her lips. Had he just described her butt as a “confounding variable”? Was being “too comfortable” a design flaw? A scientific problem that had contaminated his precious data?

Mirko, on the other hand, doubled over, choking with laughter. The sound that came out of her was a howl, a scream of pure, unadulterated joy that made the windowpanes vibrate. She slid down the wall to the floor, clutching her stomach, completely incapacitated, her muscular body shaking with spasms of hilarity.

“I can’t… I can’t breathe!” she gasped, tears streaming down her cheeks, pounding the floor with her fist. “‘Too… comfortable’! Oh my god! I’m going to die right here!”

It took her a full minute to regain some semblance of control, though small hiccups of laughter still escaped her, shaking her body. She got to her feet with difficulty, wiped her eyes with the back of her hand, and looked at Izuku, who was watching her with a slightly confused expression, not understanding what part of his methodological analysis was so funny.

“You know, squirt…” Mirko said, her voice still trembling with laughter. “You’re absolutely right. A true scientist cannot, under any circumstances, base his conclusions on incomplete and contaminated data.”

She turned and looked at Yu, who was still sitting on the couch in a state of catatonic shock, alternating between wanting to strangle Izuku and wanting to disappear from the face of the earth.

“You see it, don’t you, Yu?” Mirko continued, her tone now filled with a terrible, twisted logic. “This is bigger than you. You need a new test. He has to do it again, but this time, with clear intent and taking proper, detailed notes. For the sake of progress!”

She approached Izuku, her face lit up with the energy of her idea, amusement replaced by a manic enthusiasm.

“I have a plan!” she announced, snapping her fingers. “Let’s go back to the Dome! Right now! I urgently need to test my new crushing impact theory, and you,” she said, turning and pointing at Yu with a thumb over her shoulder, “desperately need the kid to touch your butt. We can’t let scientific malpractice stand in the way of a discovery of this magnitude!”

Yu looked in horror at the two people in her apartment. The hyperactive battle rabbit and the mad scientist with anatomical fixations. They were standing there, together, side by side, planning a new and humiliating training session to “collect data” on her butt with terrifying enthusiasm.

“No,” Yu said, her voice barely a whisper. “Absolutely not.”

Mirko didn’t even look at her. “Come on, squirt, grab your notebook! We have to document this properly! We could be writing history!”

She grabbed Izuku by the arm, who, already lost in the possibilities, didn’t even resist.

“I’m not going anywhere,” Yu insisted, getting up from the sofa. “This is my apartment, and it’s my… my…”

Yu Takeyama’s quiet Sunday morning had just been kidnapped and taken to an insane laboratory run by a crazy rabbit. There was no escape. There was no refuge. Her life had been taken over by the strangest and most embarrassing science in the world.