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The afternoon sun beat down on a small, secluded park in Musutafu, casting long shadows over a scrawny boy with a mop of unruly green hair. Twelve-year-old Izuku Midoriya was currently engaged in a battle against a rusted set of monkey bars. He wasn't swinging on them; he was trying to use them as an anchor for a series of clumsy, labored squats. His legs trembled like reeds in a hurricane, and his breath came in ragged, wheezing gasps.

"Ninety... four... ninety... five..." he squeaked, his voice cracking.

"You call those squats? My grandma kicks harder than that, and she’s been dead ten years!"

The voice was like a whip-crack. Izuku jumped so violently that he lost his grip on the bars and tumbled backward, landing squarely on his backside with a dull thud. He scrambled to sit up, his large green eyes wide with terror, only to find a towering figure standing over him.

It was Rumi Usagiyama—the No. 5 Hero, Mirko. She was a vision of raw, kinetic energy. Her long white rabbit ears flickered with every ambient sound, and her crimson eyes bored into him with an intensity that made Izuku feel like a carrot about to be shredded. Her tan skin glistened with a light sheen of sweat, and her muscular, well-defined legs looked like they were carved from marble.

"M-M-M-Mirko!" Izuku shrieked, his face turning a shade of red that rivaled her eyes. "The Rabbit Hero! You're... you're here! In this park! Why are you here? Are you on patrol? Is there a villain? Should I evacuate? I—"

"Zip it, kid! You're vibrating so fast you're gonna clip through the pavement," Rumi barked, though a smirk played on her lips. She crossed her thick, toned arms over her chest, the yellow crescent moon on her leotard shifting with the movement. "I’ve been watching you for ten minutes. You’ve got the spirit of a lion and the body of a wet noodle. What’s a shrimp like you trying to accomplish with those half-baked kicks?"

Izuku fumbled with his notebook, which had fallen out of his pocket. "I... I want to be a hero! Even if I'm... even if I don't have a flashy Quirk, I have to try! I need to be strong!"

Rumi snorted, but it wasn't unkind. She took a step closer, her massive thigh muscles flexing. "A hero, huh? Well, you’re doing it all wrong. You’re trying to move like a brawler, but you’ve got the build of a jumper. If you want to survive out there, you need to stop thinking with your head and start thinking with your heels. You want to learn how to actually use those legs?"

Izuku froze. His brain seemingly short-circuited. "Y-you mean... you'd help me? But I'm just a kid! And you're a Top Ten hero! Your time is incredibly valuable, and the economic opportunity cost of training a Quirkless middle schooler is—"

"Shut up before I kick you into next week," Rumi laughed, a wild, boisterous sound. "I like your eyes, kid. They aren't dead like most people's. Meet me at this address on Saturday morning. Don't be late, or I'll use you as a punching bag."

***

The first few weeks at Rumi’s personal gym were a blur of pain and humiliation for Izuku. The gym was a minimalist space—high ceilings, reinforced flooring, and heavy bags that looked like they had been through a war zone.

"Lower! I want to see those glutes burning!" Rumi shouted, leaning against a wall while Izuku struggled through a set of lunges.

Izuku was currently at eye-level with Rumi’s legs as she demonstrated a proper stance. He found himself staring, mesmerized by the sheer density of her muscles. The way her thigh-high boots gripped her calves and the sheer power radiating from her was overwhelming. He didn't realize he was staring until a gloved hand smacked the back of his head.

"Oi! My eyes are up here, pipsqueak!" Rumi teased, a predatory grin on her face.

Izuku turned a shade of purple. "I-I'm sorry! I was just... analyzing the muscle fibers! The way your quadriceps engage during the eccentric phase of the movement is—"

"Yeah, yeah, keep telling yourself that," she chuckled, walking circles around him like a shark. "I know I’m a masterpiece, kid. You can’t help but stare at the best legs in the business, right? Don't worry, you’ll have plenty of time to admire the view while you're doing five hundred more of these. Maybe one day you'll have a backside half as good as mine, though I doubt it. This took years of kicking villains through brick walls!"

"I wasn't! I mean, I was, but not like that!" Izuku squealed, his hands flying up to cover his face.

"Relax, I’m messing with you," she said, giving him a playful shove that nearly knocked him over. "But seriously, look at the way I pivot. If you don't turn your hips, you're just gonna break your own toes. Watch."

She exploded into motion, her leg a white-and-purple blur as she delivered a roundhouse kick to a heavy bag. The sound was like a gunshot. The bag didn't just swing; it folded in half and flew off its chain, slamming into the far wall.

Izuku’s jaw hit the floor. "Wow..."

"That’s the goal," Rumi said, wiping her brow. "Now, get back to work. And stop looking at my ass, you’re too young for that kind of heart attack."

***

As the months passed, the dynamic shifted. The initial terror Izuku felt began to melt into a deep, albeit shaky, confidence. They shared moments of levity—like the time Rumi tried to teach Izuku how to eat a "hero’s breakfast" and he ended up nearly choking on a massive protein shake, or when Rumi accidentally kicked a hole through her own ceiling while trying to swat a fly.

However, during a particularly grueling session in late autumn, the atmosphere changed. Izuku was sluggish. His movements, usually becoming crisp, were heavy and uncoordinated. He missed a kick on the pads Rumi was holding and stumbled, falling to his knees.

He didn't get up immediately. He just stayed there, head hanging low, his small shoulders shaking.

Rumi dropped the pads. Her long ears twitched, sensing the shift in the air. "Hey. Scrub. What’s the deal? You’re moving like you’ve got lead in your shoes today."

"I'm fine," Izuku whispered, his voice thick. "Just... tired."

"Don't lie to me," Rumi said, her voice dropping the playful edge. She walked over and sat down on the floor right in front of him, crossing her legs. "I didn't take you on because you were a good liar. I took you on because you were honest. Talk."

Izuku looked up, and Rumi felt a rare pang of something soft in her chest. His eyes were brimming with tears, his freckled face contorted in a mask of pure, unadulterated exhaustion.

"It's just... is it even worth it?" Izuku sobbed, the floodgates finally opening. "At school, everyone says I'm nothing. They call me 'Deku.' They say a Quirkless person is just a hurdle for everyone else to jump over. And I come here, and I try so hard, but I’m still just this... this scrawny kid. I feel like I'm running a race where the finish line keeps moving further away, and everyone else has a head start, and I'm just... I'm so tired of being the one who fails."

He buried his face in his hands, his small frame racked with sobs. "I want to be like you. I want to be strong and brave and never afraid. But I'm just me. And 'me' isn't enough."

The gym was silent for a long moment, save for the sound of Izuku’s crying. Rumi didn't move. She didn't offer a platitude or a joke. She waited until the worst of the storm had passed.

"You think I was born like this?" she asked quietly.

Izuku looked up through blurry eyes.

"I grew up in a place where people told me I was too wild," Rumi said, looking at her own scarred knuckles. "They told me a girl with a rabbit Quirk should be 'cute' and 'supportive.' They told me I’d get myself killed if I tried to fight like a brawler. I spent my whole life being told I was doing it wrong. But you know what? I didn't give a damn. Because the only person who gets to decide if I'm enough is me."

She reached out, her large, calloused hand cupping the back of Izuku’s neck. It was a firm, grounding touch.

"Listen to me, Izuku. Society is full of people who want to put you in a box because it makes them feel safer. They want you to stay small so they don't have to look up at you. But you've got something most of those 'strong' kids at your school don't have. You’ve got the guts to show up here every day and let a pro hero kick the crap out of you. You've got the heart to keep swinging when your legs are giving out."

She leaned in, her red eyes burning with a fierce, protective light. "You aren't 'just' you. You're the kid who's going to prove them all wrong. But you can't do that if you're busy agreeing with them. You’re not a hurdle, kid. You’re a goddamn landmine. They just haven't stepped on you yet."

Izuku wiped his eyes with his sleeve, a small, hiccuping breath escaping him. "You... you really think so?"

"I don't 'think,' I know," Rumi barked, standing up and pulling him to his feet with one hand. "Now, dry those eyes. Heroes don't cry because they're weak; they cry because they've been strong for too long. Take a five-minute break, then we’re doing sprints. And if I see one more tear, I’m making you do them while carrying me on your back."

Izuku let out a watery laugh. "I don't think I could lift you, Mirko-san."

"Not with that attitude, you won't! I’m pure muscle, kid, I’m heavy as a tank!" She slapped him on the back, nearly sending him flying.

As the session wound down an hour later, the sun was beginning to set, painting the gym in hues of orange and purple. Izuku packed his yellow backpack, feeling lighter than he had in weeks. The weight on his chest hadn't disappeared, but it felt manageable now, like a weight he could eventually lift.

He walked toward the door where Rumi was leaning against the frame, watching the sunset. He stopped, hesitating. He looked at his feet, then at her.

"Mirko-san?"

"Yeah, kid?"

Before he could lose his nerve, Izuku stepped forward and wrapped his arms around her waist. He was so short that his head only reached the bottom of her ribcage. It was a clumsy, desperate hug, born of immense gratitude and a newfound sense of belonging.

Rumi froze. Her ears shot straight up, and for a second, the fiercest woman in Japan looked completely lost. She stared down at the green curls pressed against her stomach. Slowly, almost tentatively, she rested a hand on his head, ruffling his hair.

"Whoa, okay. Getting mushy on me now?" she teased, though her voice was uncharacteristically soft.

"Thank you," Izuku mumbled into her suit. "For everything. I won't give up. I promise."

"You better not," she said, gently nudging him away. "If you quit now, I'll have to hunt you down, and trust me, I’m a very good hunter. Now get out of here. Go do your homework or whatever it is kids do."

Izuku nodded vigorously, a bright, genuine smile breaking across his face. "Yes, ma'am! See you Tuesday!"

He turned and bolted down the street, his legs moving with a rhythmic bounce he hadn't possessed that morning.

Rumi watched him go until he was a tiny green speck in the distance. She rubbed the back of her neck, a faint blush creeping onto her cheeks. "Jeez... what a weird kid."

She turned back into the gym, her gaze falling on the heavy bag Izuku had been practicing on. There was a small, barely visible dent near the bottom—the first real mark he’d ever made.

Rumi grinned, her teeth white and sharp. "Landmine, indeed."

She walked over to the sound system, cranked up a heavy rock track, and began her own workout. As she leaped into the air, her powerful legs coiled and released like springs, she couldn't help but think that the future of heroics might just be a little more interesting than she’d expected.

And if anyone caught the No. 5 Hero humming a cheerful tune between her ferocious kicks, well, she’d just have to kick them through a wall to keep the secret.