Chapter 4: The Sound of the Engine
The architecture of UA High School was a masterclass in psychological intimidation. To the average teenager, the towering glass walls and the iconic "U.A." gate were symbols of prestige. To Kaito Enma, they were the walls of a high-tech pressure cooker.
He stood at the entrance, his hands buried deep in the pockets of Juro's old trench coat. He wasn't looking at the building; he was listening to it. Through the soles of his boots, his Sonar picked up the deep-frequency hum of the city-sized campus. He felt the vibration of high-speed elevators, the rhythmic thrum of massive air filtration systems, and the erratic, frantic heartbeats of three hundred examinees.
The air here was too clean. It tasted of filtered oxygen and expensive floor wax, a jarring contrast to the metallic, salt-crusted air of the Grey District.
As he moved toward the auditorium for the written exam, he felt a localized spike in temperature to his left. He didn't turn his head. He didn't need to. His thermal sensing, a byproduct of the Thermal Overclock, mapped a boy with explosive, spiky blonde hair walking with the swagger of a predator. The boy's internal temperature was naturally high, a simmering engine of nitroglycerin sweat.
"Don't look at him," Kaito reminded himself. "You are a ghost. You are an engine in the shadows."
The Silent Frequency: The Written Exam
The auditorium was a cathedral of academic anxiety. Kaito sat at his assigned desk, feeling the cold, polished wood beneath his palms. Around him, the air was thick with the scent of graphite and the frantic biological markers of stress.
He opened the exam booklet. The questions were a minefield—physics equations that required a university-level understanding of force, hero ethics that demanded a nuanced grasp of the law, and complex linguistics. Juro had taught him how to survive, how to break a man's ribs without breaking his own hand, and how to scavenge a meal from a locked warehouse. He hadn't taught him the formal syntax of the elite.
Kaito closed his eyes. He let his head hang as if in deep thought, but he was shifting his perception.
He didn't send out a pulse. That would be too loud, too noticeable for any proctors with sensory quirks. Instead, he tuned his Sonar into a passive receiver. He narrowed his "hearing" until the room's ambient noise vanished, leaving only the sound of friction.
Scritch. Zip. Scritch-scritch.
He heard it. Four rows ahead, a girl with a high ponytail was writing with a rhythmic, unwavering confidence. Her heart rate was a steady 60 beats per minute. She wasn't guessing; she was reciting.
Kaito focused on the mechanical drag of her pen. In his mind, the sound translated into shapes. Every character had a different acoustic signature. A long stroke for 'Kinetic' sounded like a low-frequency hum; a quick flick for 'Option B' sounded like a sharp click against the grain of the paper.
He wasn't just copying. He used her rhythm as a foundation, cross-referencing her answers with the erratic, desperate scribbles of the students around her. When five confident heartbeats in the room all produced the same acoustic pattern for Question 12, Kaito knew the answer was absolute. He translated the sounds back into logic, filling out his paper with the cold precision of an algorithm.
By the time the proctor called for the end of the exam, Kaito's brain felt like it had been dipped in acid. The mental effort of translating sound into language for sixty minutes had pushed his internal temperature up by three degrees. A thin, almost invisible wisp of steam curled from his collar.
He stood up, his legs slightly shaky. He had played the middle ground. He wouldn't be the top scorer—that would invite investigation. He would be in the top ten percent. The "Invisible Elite."
Zero-Ground: The Staging Area
The transition to the practical exam was a visceral shift. Kaito stood at the massive gates of Battle Center B, his trench coat discarded. He wore a black compression shirt that clung to his frame, revealing the corded, efficient muscle he had built in the warehouse.
The atmosphere was electric. Present Mic stood atop a podium, his voice booming through the speakers, hitting Kaito's Sonar like a physical hammer.
"ALRIGHT, CANDIDATES! START!"
The gates groaned open. While the other students hesitated, looking for a countdown, Kaito's engine was already primed.
"Thermal Overclock: Two Percent," he whispered.
He didn't need much yet. Just enough to jumpstart his nervous system. He lunged forward, his boots cracking the asphalt. He was through the gates before the other examinees had even processed the command.
The city was a labyrinth of concrete and steel. Kaito didn't look for the robots; he listened for them. He heard the hydraulic hiss of a 2-Pointer in an alleyway to his right. He felt the vibration of a 3-Pointer's treads two blocks ahead.
He rounded the corner, coming face-to-face with a 2-Pointer. Its sensors whirred as it locked onto him.
Kaito didn't slow down. He closed his eyes, his Sonar mapping the robot's internal frame. He heard the resonant frequency of the central axle—a high-pitched metallic whine.
He dropped his internal temperature instantly—the Low-Temp Mode. His muscle fibers densified, turning his body into a heavy, blunt instrument. He ducked under the robot's claw and delivered a short, sharp palm strike to its chassis.
CLANG.
The vibration traveled from his hand into the robot's core. The machine didn't explode; it simply stopped. The internal gears, caught in the frequency of Kaito's strike, shattered into fine metallic dust.
"Two points," Kaito muttered, his voice a rasp.
He didn't stay to watch it fall. He snapped back into High-Temp Mode, his body radiating a sudden wave of heat as he accelerated toward the next target.
The Redline: 45 Villain Points
For the next eight minutes, Kaito was a ghost in the ruins.
He played a dangerous game of biological doping. He would enter a 60-second "Redline" burst, heating his blood until his skin turned a bruised, violent red and steam roared off his shoulders. In this state, he was a blur of lethal efficiency. He moved too fast for the robots' optical sensors to track.
He intercepted a cluster of three 3-Pointers in a plaza. He used the Sonar to find the "Shatter-Point" of the ground beneath them. He slammed his heel down, channeling a burst of kinetic heat into the asphalt. The ground buckled, the resonant shockwave snapping the robots' delicate leg-struts like dry twigs.
Points climbed: 15... 28... 36... 45.
But the toll was heavy. His vision was beginning to tint red. The "Brain Fry" was approaching. He could feel the lactic acid building in his thighs, a burning sensation that told him his muscles were beginning to cook.
He dropped back into Low-Temp Mode, leaning against a wall in an alleyway. He was gasping for air, the steam from his breath thick and white in the cool afternoon air. He needed a moment to vent. He checked his pulse—180 beats per minute. He was redlining.
The Zero-Pointer: Rescue by Chance
Then, the world began to move.
A deep, tectonic groan shook the faux-city. It wasn't a robot; it was a disaster. The Zero-Pointer emerged from behind a skyscraper, its massive, rusted frame blocking out the sun. It was a titan of iron, designed to be an insurmountable obstacle.
The students around Kaito broke. They fled in a panicked wave, their heartbeats a chaotic rhythm of terror. Kaito turned to join them, his 45 points secured. He had done enough.
But then, his Sonar picked up a discordant note.
Thump-thump. Thump-thump.
It was a heartbeat, trapped under a pile of rubble fifty yards away. A girl with a bob cut was pinned beneath a slab of concrete. The Zero-Pointer's massive tread was descending, a slow-motion execution.
Kaito's stomach lurched. The "Hunger" in his gut told him to run, to save his own heat. But Juro's voice, a memory etched into his very cells, screamed louder.
"A Hero saves the ones the world forgets!"
Kaito's teeth ground together so hard they nearly cracked. He pivoted on his heel, his eyes glowing with a desperate, golden fire.
"MAX OVERCLOCK: TEN PERCENT!"
The air around him distorted as the heat spiked. He didn't just run; he tore the air apart. He arrived at the girl's side in a fraction of a second, the friction of his movement singeing the fabric of his shirt.
He didn't try to lift the slab. He didn't have the leverage. Instead, he used the Doping logic. He dropped his internal temp to the absolute minimum for a millisecond, densifying his fist, and then snapped it back to the absolute maximum.
"Thermal Snap: Shatter-Point!"
He struck the concrete. The extreme temperature shift—the "Biological Shockwave"—hit the slab at its resonant frequency. The concrete didn't just break; it turned to sand.
He scooped the girl up, her weight a mere suggestion to his Overclocked muscles. He vaulted over a collapsed wall just as the Zero-Pointer's tread pulverized the earth where they had been standing.
He set her down two blocks away. He was shaking. His skin was hissing as the sweat evaporated instantly. He felt a sharp, metallic tang in the back of his throat—the taste of his own blood.
"You… you saved me," she whispered, her eyes wide with shock.
Kaito didn't look at her. He couldn't afford to let her see the red tint in his eyes or the predatory way his chest was heaving. He turned and walked into the dust, his 20 rescue points secured by a whim of conscience he hadn't known he possessed.
The Result
The digital scoreboard flickered, the blue light reflecting off the sweat-streaked faces of the exhausted candidates. The silence in the hall was heavy, broken only by the sound of heavy breathing and the distant hum of the facility's cooling fans.
Kaito kept his back against a cold concrete pillar, his lungs still burning from the oxygen debt of his final Max Overclock. He raised his eyes just as the final rankings locked into place.
Rank Name Villain Points Rescue Points Total
1 Bakugo Katsuki 77 0 77
2 Kirishima Eijiro 39 35 74
3 Uraraka Ochaco 28 45 73
4 Shiozaki Ibara 36 32 68
5 Kaito Enma 45 20 65
A ripple of whispers broke the silence.
"Who is Kaito Enma?" a boy with a bird-like shadow muttered, checking his own rank. "I didn't see him in the main plazas. Forty-five villain points... he must have been hunting in the blind spots."
"Look at those rescue points," a girl with a ponytail whispered, her eyes shifting from the screen to the crowd. "Twenty points exactly. It's a clean score. He didn't just stumble into a rescue; he Five, Kaito thought, his pulse finally slowing. Low enough to be a shadow. High enough to be a threat. Juro, the engine held together. Barely.
The Five-Day Wait
A woman in a sharp, formal suit stepped onto the central podium, her voice amplified by the room's acoustics.
"Attention, candidates! The practical and written portions are officially concluded. Your performance today will be reviewed by the faculty board alongside your academic records. Final admission decisions—whether you are 'In' or 'Out'—will be mailed to your registered addresses in exactly five days. You are dismissed."
The crowd dispersed like a receding tide. Kaito walked out of the gates, the evening air hitting his skin like a blessing. He didn't take the train. He walked the long miles back to the warehouse in the Grey District, his muscles screaming with every step.
For the next five days, Kaito lived in a state of suspended animation. He spent his hours in the warehouse, cleaning Juro's old equipment and eating massive quantities of cheap, high-protein mash to replenish his depleted fat stores. The "Hunger" was a constant companion, gnawing at his stomach as his body repaired the micro-tears in his muscle fibers caused by the 10% Overclock.
On the fifth day, a heavy envelope slid through the mail slot in the warehouse door.
Kaito sat at the small wooden table where he and Juro used to eat. His hands, still stained with the grease of the warehouse, shook slightly as he tore the seal. A small, circular device tumbled out onto the wood. It blinked once, twice, and then a holographic projection erupted into the dim room.
"I AM HERE... AS A PROJECTION!"
The voice was like a thunderclap. The image of All Might, the Number One Hero, stood tall in the center of the dusty floor.
"Young Enma! You performed with the tenacity of a true warrior! In the written exam, you showed a keen, analytical mind. But in the practical... you showed the heart of a Hero! Even when it gained you nothing, you moved to save a fellow student! With a total of 65 points, you have secured your place in the hero course!"
All Might's grin seemed to grow even wider, his hand pointing directly at Kaito.
"Welcome, Kaito Enma. You are now a student of Class 1-A! This is your Hero Academia!"
The hologram vanished, leaving the warehouse in a heavy, ringing silence. Kaito sat in the dark for a long time, the words Class 1-A echoing in his mind. He looked at the spot under the floorboards where Juro was buried.
"I'm in," Kaito whispered, his internal temperature rising just enough to let a single wisp of steam escape his lips. "The engine is officially running."
The Sin Eater had entered the Lion's Den.