The sound of the slap sharp and definitive hung in the alley's stale air. It echoed off the damp bricks and overflowing dumpsters before fading, leaving a thick silence. Yu Takeyama stood motionless, her back to him, her gigantic form now reduced to its normal size. The heat rising up her neck wasn't just from her Quirk's decompression; it was pure, searing shame that burned her ears.
It wasn't the pain, which was negligible, nor the humiliation of the act itself. It was the audacity. The absolute, baffling lack of hesitation with which this boy, a total stranger, had spanked her with the confidence of a professional evaluating his work.
Slowly, as if a sudden movement might break the spell of disbelief, she turned. Her eyes, which moments before had shone with the euphoria of her successful debut, were now a battlefield of fury and confusion. Her hand rose instinctively, not to rub the spot, but to confirm it was all real.
"You..." she began, her voice a low, dangerous hiss. The words got stuck. She tried again. "You... were you sure that was going to work?"
Izuku Midoriya, who until that moment had worn the expression of a scientist observing a successful experiment, blinked as if coming out of a trance. Then he nodded with a conviction that infuriated her even more.
"Well, about a seventy percent certainty, more or less," he admitted, adjusting a non-existent tie. His tone was as casual as if he were discussing the weather forecast. "But the logic was sound. My Quirk enhances things through physical contact. To reverse an unwanted effect, like uncontrolled growth, I needed a corrective action. A firm slap on the affected area is the most classic and documented training method."
Yu's jaw felt like it might unhinge. "Logic? Corrective training? Are you telling me you based the decision to... touch me like that... on a simple guess?"
"It wasn't a guess," Izuku corrected her, his almost academic seriousness like adding fuel to a fire. "It was a well-founded hypothesis. I have quite extensive knowledge on the subject, in fact."
She crossed her arms over her chest. "Oh, really? Enlighten me. What subject are you an expert in, exactly?"
Izuku stood a little straighter, adopting the air of a scholar about to present his thesis.
"In the appreciation of rear ends, of course," he declared with terrifying sincerity. "My knowledge isn't anecdotal; it's based on years of rigorous study: manga, action figures, and some late-night variety shows. I've analyzed thousands of panels, studied proportions, curvature, implicit density, the response to impact... I could consider myself a certified connoisseur of rear ends. And yours," he said, his gaze dropping for an instant, not with lust, but with clinical appreciation, "is top-tier. Exhibition quality. That's why I knew such a well-formed structure would respond favorably to the stimulus."
A dead silence fell over the alley. Yu stared at him, her brain trying to process the cascade of madness she had just heard. She was trapped between slapping that smug look off his face, screaming until her voice gave out, or just sitting on the dirty asphalt and having a full-blown nervous breakdown. This teenager hadn't just spanked her, he was now lecturing her on the quality of her butt as if it were a vintage wine. And the worst part was that, from his sincerity, she felt he truly believed he had done her a favor.
"You..." she began again, searching for a word that could encapsulate the magnitude of what she was witnessing. "You're unbelievable."
"Thank you. I do what I can for the common good," he replied with a modesty so out of place it made her want to tear her hair out.
Fortunately, the sound of approaching sirens snapped her out of her stupor. Her debut. Her first official day. If the police, or worse, reporters, found them here discussing the "exhibition quality" of her backside with a teenager, her career could be over before it began. The mental image of the headline made her turn pale: New Heroine Mt. Lady Involved in Bizarre Butt-Slapping Incident with a Minor.
"Listen," she said, her tone shifting to professional and urgent as she invaded his personal space. "Nobody. Absolutely nobody can know about this. Understand? If this gets out, my reputation will be ruined. It would be the end of my career."
Izuku blinked, her seriousness finally piercing his analytical bubble. He nodded, his expression now grave. "Understood. Your secret is safe with me. Professional discretion."
Yu watched him, scrutinizing his face. She saw sincerity, not malice. She saw the boy who, because of her fall, had just lost his job. And beyond the panic, she felt the memory of that strange surge of power that had coursed through her when he touched her. Just before shrinking, she had felt stronger.
Her ambition overcame her shame. This weird kid wasn't just a risk; he was an unknown variable, a potential shortcut to the top in the competitive world of heroes.
"We have to get out of here now," she said, making a life-changing decision. "You can't stay. If the police find you, they'll ask questions. And you..." she looked him up and down, "don't seem like a good liar."
"Lie? Why? I'd simply explain the scientific basis of my—" he started.
"No!" she cut him off, grabbing his arm. "You're not explaining anything to anyone. You're coming with me. Now."
"Where are we going?" he asked, stumbling as she dragged him out of the alley.
"To my agency," she replied, her mind racing. "I have a lot of questions. And you have the answers, even if you're too weird to realize it. Let's go."
They headed to the train station in a tense silence. Yu walked a yard ahead, setting a fast pace, and Izuku followed, casting furtive, analytical glances at her rear—like an artist admiring his own sculpture. Every time she caught him, he'd just offer a small, approving smile that made her incredibly nervous.
"Can you stop doing that?" she snapped without stopping.
"Doing what?"
"That! Staring!"
"I'm sorry," Izuku said, not sounding sorry at all. "I'm just evaluating the results. There appear to be no adverse side effects. The structure has returned to its original state without losing integrity. It's fascinating."
Yu clenched her fists and walked faster.
On the platform, the normality of the outside world made their situation feel even more surreal. She bought two tickets, paying for Izuku's before he could pull out his wallet. Inside the train car, they found two seats facing each other.
Yu was the one who broke the silence. "I still don't know your name."
"Izuku Midoriya."
"Yu Takeyama," she replied out of reflex. "Though I guess you already know the other one."
"Mt. Lady," he said with an almost religious reverence and a glint of admiration that brought a faint blush to her cheeks. "Your debut was incredible. The Canyon Cannon was perfect execution. An impeccable angle to maximize impact without causing excessive structural damage. Your control when you fell was textbook."
"Thanks," she said, surprised by the precision of his analysis. "You know a lot about Quirks?"
"Only what I read and analyze. I'm a fan. Or I was," he corrected himself, a shadow of sadness crossing his face. "My Quirk isn't for fighting."
"I see," she said. "What will you do about your job now?"
Izuku shrugged. "I guess I'll look for another one. Though I doubt anyone will trust me with their dog after today. Mrs. Tanaka is going to kill me. Her poodle, Princess Fluffy III, has anxiety."
Yu felt a pang of guilt, quickly replaced by ambitious calculation. This wasn't a problem; it was an opportunity.
They arrived at her stop and walked a few more blocks to her apartment. It was in a functional building in a quiet neighborhood. The inside was spacious and bright but had the impersonal grace of someone who spent little time at home. It was the home of a rookie investing more in her career than in luxuries.
"It's not much, but it's my base of operations," Yu said, dropping her bag on a chair. "Want something to drink? I have water or... well, I only have water."
"Water is fine, thank you," Izuku replied, looking around with curiosity.
While she was in the kitchen, he walked over to a bookshelf and saw photos of her with other girls, probably from her student days. A glimpse of the person behind the hero.
She returned with two glasses of water and they sat on the sofa, keeping a safe distance.
"Alright, Midoriya. Let's talk about your Quirk. No theories about butts. Just the facts. What is it, exactly?"
"It's called 'Train," he said. "On my official registration, it's classified as an animal empathy Quirk. It lets me understand their needs and give them simple commands. Until today, I thought it only worked on animals."
"But it affected me," she said, disbelief still in her voice. "And I felt... A power boost. Temporary, I know. But it was real. Can you do it again?"
Izuku looked at her and saw the same naked ambition that had driven her in battle. "I don't know. I'd never done it on a person before. When you fell and I touched you, I just felt a connection. As if my power understood your body needed to be bigger and stronger, and it just gave it that. It was instinctive. And to reverse it, instinct told me the same point of contact needed an opposite command."
A faint blush colored their cheeks, but neither looked away.
"And do you think you could enhance other things?" she pressed. "Make someone stronger? Faster?"
"I have no idea," Izuku repeated, now fully engrossed in the problem. "I suppose it depends on the point of contact. Your rear end Is perfect. Maybe if I touch your elbow, it would just make it an excellent elbow. We might need a larger surface area for a systemic effect."
Yu stared at him, unsure if she should be flattered or offended. He was a diamond in the rough wrapped in dirty newspaper.
"Listen, Midoriya," she said, leaning forward conspiratorially. "You lost your job because of me, and you don't have a plan B. And I need to understand your power. If it's what I think it is, it could be the key to making it to the top ten."
The ambition in her voice sounded incredibly attractive to Izuku, who had given up on his own dream.
"I'm offering you a deal," she continued. "Forget the dogs. Come work for me. Officially, you'll be my personal assistant. Unofficially," she gestured between them, "you'll be my personal test subject. And I'll be yours. Together, we'll discover the limits of your Quirk. In return, you'll get a salary and be closer to the world of heroes than you've ever been."
The offer was insane. Deeply unethical. And the best one Izuku Midoriya had ever received.
He looked at Yu Takeyama. He saw Mt. Lady, the ambitious woman, and the potential boss offering him a way out.