The ceiling was unfamiliar.
That was Rei Mizuki's first thought as consciousness slowly dragged him back from whatever dark void he'd been floating in.
'Where... am I?'
His body felt heavy. Not the kind of heavy that came from exhaustion or injury—he knew that feeling intimately. This was different. Lighter, somehow. Smaller.
Rei's eyes tracked across the ceiling, noting the plain white paint, the small crack running from the corner toward the center. A cheap apartment ceiling. The kind you saw in lower-income housing districts across any major city.
But that wasn't right.
The last thing he remembered was—
The warehouse. Concrete floor slick with something he didn't want to think about. The job had been simple: eliminate the target, collect payment, disappear. Clean. Efficient. He'd done it a hundred times before.
But the doors had slammed shut. Twelve men, maybe fifteen. All armed. All pointing at him.
'A Trap'.
'They wanted to get rid of him after all these years of dirty work he did for them'
Rei's hand moved to his chest instinctively, searching for the bullet wounds, the knife cuts, the—
Nothing.
His hand was small. Too small.
'What the hell?'
He sat up slowly, and the room spun for a moment before settling. A small bedroom, barely ten square meters. A desk with textbooks stacked haphazardly. A closet with the door slightly ajar, revealing a middle school uniform. Posters on the wall—heroes. People in colorful costumes striking dramatic poses.
His eyes locked onto one poster in particular.
All Might.
The Symbol of Peace, grinning with that trademark smile, one fist raised to the sky.
'No way.'
Rei's breathing quickened. His hands—small, unmarked by scars—came up to his face. Smooth skin. No calluses from years of holding weapons. No burn marks from that job in Osaka. No—
A mirror. There was a small mirror on the desk.
He stumbled over to it, his legs unsteady, and looked at his reflection.
A kid stared back at him. Maybe fifteen years old. Messy black hair that fell just past his ears. Dark eyes that somehow still carried that same cold look he'd perfected over years in his previous life. A lean face that would probably be called handsome once he grew into it.
But it wasn't his face.
Or rather, it was, but it wasn't.
'I died.' The thought came with absolute certainty. 'I died in that warehouse. I remember... I remember fighting until the end. I remember smiling bitterly because I knew i wouldn't make it out alive.'
So why was he here?
Why was he alive?
Why was he looking like some fifteen years old kid?!
And why the hell was there an All Might poster on his wall?
Rei sat back down on the bed, forcing his breathing to steady. Panic was useless. Panic got you killed. He'd learned that lesson early in his previous life.
'Think. Analyze. Adapt.'
He closed his eyes and focused inward, trying to sort through the mess of memories that were suddenly flooding his brain. Two sets of memories, actually. Two lives overlapping like a badly edited film.
One set belonged to him—to the assassin who'd died in a warehouse in Tokyo. Twenty-eight years of killing for money, of living in the shadows, of perfecting the art of death.
The other set belonged to someone else. A kid named Rei Mizuki. Fifteen years old. Orphan. Living alone in a small apartment in Musutafu City. Middle school student preparing for high school entrance exams.
'Musutafu City.'
That name sent a chill down his spine.
Because Rei Mizuki—the assassin from Earth—knew exactly where Musutafu City was.
It was the main setting of My Hero Academia.
'No. No way. That's not possible.'
But even as he thought it, more memories surfaced. Memories of this world. A world where 80% of the population had superpowers called Quirks. A world where heroes and villains were real. A world where people like All Might existed.
A world that had been a manga and anime in his previous life.
'I reincarnated.' The thought was absurd, but it was the only explanation that made sense. 'I died and somehow ended up here. In My Hero Academia. As a fifteen-year-old kid.'
Rei opened his eyes and looked at his hands again. Small. Young. Unmarked.
A second chance.
He almost laughed. The universe had a twisted sense of humor. An assassin—someone who'd spent nearly three decades taking lives—given a fresh start in a world of heroes.
'Alright.' He took a deep breath. 'First things first. Figure out what I know.'
He stood up and started pacing, organizing his thoughts.
From his—the original Rei Mizuki's—memories, he knew the basics. He was an orphan. Parents died when he was seven in a villain attack. No other family. The government provided a small monthly stipend and this apartment. He'd been living alone for eight years now.
He attended Aldera Junior High school.The same school that Izuku Midoriya and Katsuki Bakugo went to.
'Midoriya and Bakugo.' Two names that made this whole situation feel even more surreal.
According to the memories, he knew them. Not well—he kept to himself mostly—but he'd seen them around. The explosive blond kid who acted like he was better than everyone. The green-haired kid who used to have a Quirk analysis notebook and got bullied constantly.
'Which means...' Rei's mind raced. 'The story is about to start. The UA entrance exam.'
He moved to the desk and rifled through the papers scattered across it. School documents. Practice tests. And there—an application form.
UA High School entrance examination.
The date on the form made his stomach drop.
Four weeks.
The UA entrance exam was in four weeks.
'So I'm here right at the crucial moment.' Rei sat down in the desk chair, his mind spinning. 'Right before the entrance exam. Right before everything kicks off for real.'
But there was something else nagging at him. Something important in the original Rei's memories.
His Quirk.
Everyone in this world had a Quirk—or at least, 80% of people did. The original Rei Mizuki had one too.
He closed his eyes and focused, reaching for that specific memory. The memory of discovering his power. The memory of learning what he could do.
And when he found it, his eyes snapped open.
'Spider.'
That was the name of his Quirk.
Spider.
Rei stood up quickly and looked at his hands. Really looked at them. Then at the wall beside his bed. A crazy idea was forming in his mind.
'No way. It can't be that simple.'
He reached out and pressed his palm flat against the wall. Concentrated. Felt something in his body respond—some instinct that belonged to this new body, this new life.
And then he pushed off the ground.
His feet left the floor.
His hand stuck to the wall.
Rei Mizuki was standing on the wall, perpendicular to the ground, defying gravity like it was the most natural thing in the world.
'Holy shit.'
He took a step. Then another. Walking up the wall like it was a floor. The sensation was bizarre—his brain screamed that he should be falling, but his body knew better. His hands and feet adhered to the surface with perfect control.
He reached the ceiling and kept going, now walking upside down, looking at his bed from above.
'I have Spider-Man's powers.' The realization hit him like a truck. 'My Quirk... it's literally Spider-Man's powers.'
He dropped back down to the floor, landing in a crouch that would've broken his ankles in his previous life. But here, his body absorbed the impact effortlessly, muscles coiling and releasing like springs.
'Wall-crawling. Enhanced strength. Enhanced agility.' He ran through the list based on the original Rei's memories. 'The Quirk manifested when I was five. I've had ten years to get used to it.'
But there was more, wasn't there? He could feel it. Something else lurking beneath the surface.
Rei focused inward again, trying to sense the full extent of his abilities. The original Rei had trained with his Quirk, had pushed it, had learned its limits.
Enhanced senses. He could hear the couple arguing three apartments down. Could smell the ramen someone was cooking two floors below. Could feel the minute vibrations in the air when he focused.
Enhanced reflexes. His body could react to threats before his conscious mind even registered them.
Superhuman strength. Not on the level of All Might, obviously, but far beyond what a normal fifteen-year-old should have. The original Rei could lift maybe three, four times his body weight with effort.
Superhuman agility and acrobatics. His body could bend and move in ways that would make Olympic gymnasts weep.
Wall-crawling and surface adhesion. Obviously.
And one more thing. One ability that the original Rei had discovered but rarely used because it was hard to explain.
Rei held up his hand and focused on his wrist. Concentrated on that specific sensation he could feel buried in the memory.
His wrist tingled.
And then a thin, white strand shot out from a nearly invisible gland just below his wrist.
Webbing.
Organic webbing.
'I can shoot webs.' Rei stared at the strand hanging from his wrist, connected to the wall across the room. 'I can actually shoot webs.'
He gave it an experimental tug. Strong. Incredibly strong. The original Rei's memories told him the webbing could support over a thousand kilograms before snapping.
Rei dissolved the web with a thought—apparently, he could control when it disintegrated—and sat back down on his bed.
'Okay. Let me process this.'
He was in the My Hero Academia world. He had died in his previous life as an assassin and somehow ended up here as a fifteen-year-old kid named Rei Mizuki. He had a Quirk called Spider that gave him almost exactly the same powers as Spider-Man from the comics.
And the UA entrance exam—the event that kicked off the entire story—was in four weeks.
'So what do I do?'
The question hung in the air.
In his previous life, Rei had been a ghost. A weapon. He took contracts, eliminated targets, collected payment. No attachments. No connections. No purpose beyond the next job.
He'd been good at it. Damn good. One of the best in the business.
But he'd also been empty.
He'd died alone in that warehouse, surrounded by enemies, smiling because at least it was finally over.
'But now...' Rei looked around the small apartment. At the hero posters. At the UA application. At this second chance he'd somehow been given.
'Now I'm in a world of heroes.'
A laugh escaped his lips. Dry. Bitter. Because the irony was almost too much.
An assassin. A killer. Given a second life in a world where heroes were real.
What was he supposed to do with that?
'I could ignore it,' he thought. 'Just live a quiet life. Use my knowledge of the plot to avoid trouble. Maybe make some money betting on hero rankings or something.'
But even as the thought formed, he knew it was bullshit.
Because there was another thought lurking beneath it. A thought that had been growing ever since he realized where he was.
'All For One. The League of Villains. The war. The death and destruction that's coming.'
Rei knew the story. He'd watched the anime, read the manga in his previous life during the rare moments of downtime between jobs. He knew what was coming. The attacks. The invasions. The casualties.
He knew that people were going to die.
'And I could stop it. Or at least, I could try.'
The thought was seductive. Dangerous.
Because Rei Mizuki—the assassin—had never been a hero. He'd been the opposite. He'd taken lives for money, no questions asked.
But Rei Mizuki—this Rei Mizuki, the fifteen-year-old kid with spider powers and a second chance—didn't have to be the same person.
He stood up and walked to the window, looking out over Musutafu City. The sun was setting, painting the sky in shades of orange and red. In the distance, he could see the silhouette of the tallest building—probably one of the hero agencies.
'Four weeks until the entrance exam.' He clenched his fist. 'Four weeks to prepare.'
His body was different. Younger. Weaker than he'd been in his prime. But he had something now that he'd never had before.
Powers.
Real, genuine superpowers.
'The original Rei trained with his Quirk, but he was just a kid. He didn't know how to fight. Didn't know how to kill.'
But the assassin Rei did.
'So what happens when you combine my experience, my skills, my knowledge... with a Quirk like this?'
A slow smile spread across his face. Not the scary smile from his death. Something different. Something that carried a hint of anticipation.
'I guess we'll find out.'
Rei turned away from the window and started taking stock of his situation properly. The apartment was small but functional. One bedroom, one bathroom, a tiny kitchen, a living area that doubled as a training space. The original Rei had kept it clean, organized. Good.
He moved to the closet and checked his clothes. School uniforms. Casual wear. Nothing special. He'd need to get some training gear. Maybe something he could use as a makeshift costume if he was going to be testing his abilities outside.
'Money.' That was going to be an issue. The orphan stipend wasn't much. Enough to cover rent and food, but not much else. He'd need income if he wanted to properly prepare.
In his previous life, that would've meant taking contracts. But that wasn't an option here. Not if he was serious about trying this whole hero thing.
'I'll figure it out.' He always did.
Rei sat back down at his desk and pulled out a notebook. Time to start planning.
First, physical training. His body was young, still developing. He needed to build muscle, increase stamina, push his limits. The Quirk gave him enhanced capabilities, but he was still bound by human biology. Sort of.
Second, Quirk training. He needed to master every aspect of his Spider Quirk. Wall-crawling was easy—he'd been doing it for ten years. But the strength, the reflexes, the senses, the webbing—all of that needed to be pushed further. He needed to know exactly what he could do and what his limits were.
Third, combat training. The original Rei didn't know how to fight. Not really. Some basic self-defense maybe, but nothing serious. But the assassin Rei had decades of experience with dozens of martial arts, weapons training, kill techniques. He needed to adapt that knowledge to this new, younger body.
Fourth, preparation for the UA exam. He knew what was coming. The mock battle against robots. The rescue points system. He knew how to pass. But he also knew that just passing wasn't enough. If he was going to do this, he needed to stand out. He needed to make an impression.
And fifth—most important—he needed to figure out his role in all of this.
'Am I going to follow the canon timeline? Or am I going to change things?'
That was the million-dollar question.
Rei tapped his pen against the notebook, thinking.
In his previous life, he'd been a variable. An unknown factor. Someone who operated in the shadows, changing outcomes without anyone knowing he was there.
But here? In this world?
'The original Rei Mizuki wasn't in the story.' The realization settled over him like a weight. 'I checked the memories. I never interacted with Midoriya or Bakugo beyond seeing them in class. I never went to UA in the original timeline. I'm not a canon character.'
Which meant...
'I'm a variable here too.'
A variable in a story he knew by heart.
The question was: what was he going to do with that knowledge?
Rei stood up and walked to his bed, lying down and staring at the ceiling again. That same crack, running from corner to center.
'One month,' he thought. 'One month until everything changes. Until the entrance exam. Until I step into the story for real.'
'One month to decide what kind of person I'm going to be.'
'One month to prepare for a war I know is coming.'
Rei closed his eyes, exhaustion from processing two lifetimes of memories finally catching up to him.
His last thought before sleep claimed him was simple:
'I died once already. I'm not wasting this second chance.'
Tomorrow, the real work would begin.
Tomorrow, Rei Mizuki would start his journey to becoming a hero.
Or at least, something close to it.
After all, you can't erase decades of being an assassin overnight.
But maybe, just maybe, you could learn to use those skills for something better.
'I'm Spider-Man,' he thought with a hint of dark amusement. 'In the world of My Hero Academia. With the memories of an assassin and the powers of a hero.'
'This is either going to be the best second chance ever, or the most spectacular disaster in history.'
'Guess we'll find out.'
And with that, Rei Mizuki drifted off to sleep, dreaming of a future that was his to write.
----
Author's Note:
Hey everyone! Thanks for reading Chapter 1 of "As Spiderman in MHA"!
This is my entry for the Fanfic Fiesta contest, and I'm really excited to share Rei's journey with you all. If you're enjoying the story so far, please support me by:
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