The walk home from the clinic was a journey through a world Ren now saw with dual vision. The vibrant advertisements for "Quirk-Enhanced Learning!" and "Pro Hero-Endorsed Vitamins!" blared from screens, but his mind filtered them into schematics for energy sources and actuator stress tolerances. A man on the street casually extended his arm to impossible lengths to retrieve a dropped wallet; Ren's mind catalogued the potential ligament strain and counter-balanced it with a theoretical gyroscopic stabilizer.
His small hand was engulfed in his mother's. Her grip was tight, protective, a lifeline tethering him to the present. She was quiet, the doctor's words and her son's impossible declaration warring inside her.
Their apartment was a modest, sunlit box on the third floor of a weathered but clean building. It smelled of lemon cleaner and the mild floral scent of Akari's shampoo. It was a place of peace, now the site of a silent revolution.
Akari sank onto the worn sofa, pulling Ren onto her lap. She didn't cry. She studied him, her fingers gently brushing his dark hair away from his forehead.
"Ren," she began, her voice hoarse. "What you said… 'build my own'… baby, what does that mean?"
He met her gaze, his own unnervingly steady. "The doctor said I have no power in my genes. Okay. But power is just energy directed with purpose. Energy is everywhere." He pointed a small finger at the floor lamp in the corner. "Electricity. In the walls." He pointed out the window at the setting sun. "Light. Heat. Kinetic energy from movement." He tapped his own temple again. "The purpose… the direction… that comes from here. From knowing how."
Akari's breath caught. This wasn't the fantastical babbling of a child. This was a thesis, delivered with a chilling, quiet precision. "How do you know these words, Ren? These… concepts?"
He had prepared for this. A four-year-old genius would raise questions, but a four-year-old reincarnated genius would get him sent to a lab. He let a layer of childish confusion soften his eyes. "I… see it, Mama. In my head. Like puzzles. The lamp is a puzzle of light. The train outside is a puzzle of motion. I just… want to solve them."
It was enough truth to be real, enough mystery to be accepted as a strange, post-diagnosis coping mechanism. Akari's nurse-brain latched onto it—a hyper-focused cognitive development, perhaps. Her mother-heart saw the fierce light in his eyes and knew, somehow, it was more.
She hugged him again. "Okay," she whispered into his hair. "Okay."
That single word was her vow. It was the foundation of everything to come.
The next day, after her shift at the hospital, Akari didn't bring home picture books. She brought home a junior engineering kit meant for eight-year-olds, bought with a week's grocery money. It contained simple gears, pulleys, plastic connectors, and a small, safe hand-crank motor.
Ren's eyes lit up with a ferocity that stole her breath. He didn't play with the pieces. He interrogated them. In an hour, he had disassembled and reassembled the motor, intuiting its principles. In two, he had built a rudimentary, clacking conveyor belt that moved a pebble from one end of the coffee table to the other.
Akari watched, her heart pounding with a mixture of pride and fear. The diagnosis of 'Quirkless' had tried to label her son as 'less.' But here he was, creating function from chaos, speaking a language of mechanics she barely understood. He was more.
"It's inefficient," Ren muttered, frowning at his creation. "The friction coefficient of the plastic is too high. The energy transfer from the crank is lost here, and here." He pointed with a grubby finger.
That weekend, she took him to the local library. He beelined past the children's section, a small arrow shot toward destiny. He returned, staggering under the weight of three books: Basic Physics for Young Minds, The History of Engineering, and a dog-eared compendium of 20th-century mechanical inventions.
The librarian, a woman with hair that floated like seaweed (a mild aquatic Quirk), chuckled. "Aiming high, little man! Those are for much older kids."
Ren looked up, his expression deadly serious. "The information isn't older. It's just waiting."
Akari paid the late fees she knew were coming.
The apartment transformed. A corner of the living room became Ren's "workshop." Schematics drawn in crayon and, later, meticulous pencil, papered the walls. Not of dinosaurs or superheroes, but of lever systems, simple circuits, and explosive ideas for "repulsor-lift" based on his hazy, cherished memories of another life's fiction. He began peppering his speech with terms he read: torque, capacitance, tensile strength.
He was six when he made his first purposeful invention. Akari had come home exhausted, rubbing her lower back after a double shift. Ren had watched her for days. That evening, he presented her with a contraption made from the engineering kit parts, a repurposed back-massager from a thrift store, and what looked like the guts of a broken alarm clock.
"For your lumbar support," he said, holding it out. It was ugly, a nest of wires and plastic, but when she hesitantly leaned against it and he flicked a switch, a gentle, warming vibration pulsed against her aching muscles. It wasn't just functional; it was considerate.
Tears welled in Akari's eyes. Not because of the device, but because of the mind that created it. A mind that saw her pain and dedicated its immense, frightening focus to alleviating it. This was the heart the doctor hadn't scanned.
She knelt and pulled him close. "Thank you, my brilliant, kind boy."
He hugged her back, then pulled away, his business-like demeanor returning. "It's version one. The battery life is terrible. I need a better power source."
The search for a "better power source" led them to Mustafu's central scrapyard. It became their sanctuary. To Ren, it wasn't a graveyard of broken things; it was a library of components, a paradise of potential. Old car alternators became future generators. Shattered smartphones yielded precious microcontrollers. Discarded aluminum siding was the raw ore for armor plating.
Akari would negotiate with the grizzled foreman, a man with stone-like skin, while Ren, wearing oversized work gloves, would clamber through the metallic canyons, his eyes gleaming like a prospector's. He learned to see the story in the scars on the metal—a dent from a villain's impact, a clean cut from a Hero's blade. He learned which alloys were strong, which were light, which could take a beating.
He was eight, kneeling in the grease and dust, prying a cylindrical component from a wrecked sports car, when the incident happened.
A commotion erupted at the scrapyard gates. Shouts. The foreman's booming voice raised in alarm. A villain—a low-level thug with the Quirk to morph his fingers into crude, sharp hooks—was fleeing a botched robbery, and had ducked into the scrapyard to lose his pursuers. He was cornered, desperate, and now slashing wildly at the foreman, who raised his stony arms in defense.
Akari screamed, pulling Ren behind a stack of rusted refrigerators. "Stay here!"
But Ren's eyes weren't on the villain. They were on a young apprentice, maybe fourteen, who had been sorting copper nearby and was now frozen in terror, directly in the hook-man's path. The villain, seeing an easier target, turned with a snarl.
Time didn't slow. It crystallized.
Ren's body moved before his new mind could fully command it. It was the oldest instinct, reborn and rewired: Protect.
His hand closed around the object he'd just salvaged—the sports car's high-density capacitor, about the size of a soda can, with two heavy leads. He didn't have a suit. He didn't have weapons. He had physics.
He scrambled, not away, but toward a nearby junction box where the scrapyard's welding equipment was powered. With a grunt of effort, he jammed one capacitor lead into a live socket.
A violent spark erupted. The capacitor whined, charging instantly and dangerously over capacity. It grew hot in his hand.
The hook-villain lunged at the cowering apprentice.
Ren stood up. He hurled the searing-hot, overcharged capacitor.
It wasn't a good throw. It didn't hit the villain. It struck the metal chassis of a gutted bus two feet to the villain's left.
The effect was not an explosion, but a catastrophic, deafening SHUNK-CRACK-BOOM of superheated metal rupturing and a contained electrical discharge blooming like a blue star. The shockwave and spray of molten slag knocked the villain off his feet, sending him sprawling, disoriented and burned.
The foreman seized the moment, bringing a stone fist down to pin him.
Silence, broken by the sizzle of cooling metal and the villain's groans.
All eyes turned to the small, soot-stained boy standing by the junction box, his oversized gloves smoking slightly, his face pale but set.
The saved apprentice stared at him, tears cutting tracks through the grime on his face. The foreman looked from the whimpering villain to the ruptured bus to Ren, his stony jaw slack.
Akari rushed forward, gathering Ren into her arms, checking him for injuries. He was trembling, but his eyes were fixed on the scene—on the apprentice who was safe, on the villain who was neutralized.
A siren wailed in the distance. The Pros had arrived.
Later, at home, as Akari cleaned the soot from his face with hands that wouldn't stop shaking, Ren finally spoke.
"It was inefficient," he whispered, his voice small again. "Unstable. Reckless. I could have killed him. Or the apprentice. Or myself."
Akari's heart broke and swelled at once. "You saved a life, Ren."
He looked up at her, and in his eyes, she saw the birth of a terrible, beautiful resolve. "Saving a life shouldn't be a gamble. It shouldn't require a lucky throw with a makeshift bomb." He clenched his small, scraped fists. "I need a system, Mama. A reliable system. I need… I need to be better."
He looked toward their living room, toward his corner of crayon schematics and scavenged parts. The childish puzzles were over.
That night, by the light of a desklamp, Ren Saito, age eight, began drafting in earnest. Not a childish sketch, but the first, true, foundational blueprint. It was rough, filled with question marks and calculations in the margins that were far beyond his years. At the top of the page, he wrote two words, the name of the project, the shape of his promise:
IRON HEART - MARK I