One's Justice

Chapter 1

Author's note- This is my first story, so please bear with me for any faults with it. I would really appreciate constructive criticism so that I can improve my writing and storytelling skills. I am writing this story because I really like One Punch Man and My Hero Academia, and I was always interested in a crossover between the two. Unfortunately, there aren't many stories of good length on this subject, so I decided to make one of my own. That said, I hope you enjoy.

Now the story begins-

Scene 1: Tatooine Station

Izuku jogs excitedly to school, happy to use this beautiful school day to add more notes to his notebook containing statistics and analysis of various heroes. On the way, he comes across a scene of a giant villain with a beastly head attacking Tatooin Station. Three Pro-Heroes arrived to engage: Backdraft, Kamui Woods and Death Arms.

Oh, they're gonna take on that villain! I better take notes! Izuku thought.

As the giant swung his giant arms around, a huge piece of debris threatened to crush some civilians. As the terrified innocents screamed, Death Arms rushing in and caught the broke metal tower with his powerful arms.

"Wow way to go Death Arms!" A man in a business suit praised. "I wish I had a quirk that made me super strong like The Punching Hero." A man with wings on his heels mused.

"Stand back people, this is going to be dangerous!" Warned Backdraft as he extended water from his spigot-like arms, shaping them into makeshift police lines to keep everyone back.

"Wow the rescue specialist Backdraft is here? He'll make sure we're okay!" Yelled a police officer.

"Know what happened?" A passerby asked out loud. "This amateur stole someone's purse and got caught." Another man replied. "A quirk like that and he's using it for petty theft." The passerby bitterly stated.

Suddenly a group of fangirls yelled to the top of their lungs, "Kamui!" The said hero suddenly jumped in, avoiding the giant's swings. "Get away from me or I'll break you toothpick!" The villain boomed.

"Oh this is gonna be good! It's Kamui Woods! He may be new but he's making a name for himself!" Izuku excitedly exclaimed. Tch, judging by his goofy smile he must be a fanboy, a man with three T-shaped appendages sticking out of his head thought to himself.

At that moment, Kamui prepared his final move. He stretched out his limbs into several large branches to ensnare the giant villain and ultimately restore order. The villain closed his eyes and braced himself for what was coming. "OH MAN! Its his special move!" Izuku proclaimed. "The Pre-Emptive-!"

Kasumi - "Binding"

"LAQUERED CHAIN PRISON!"

But before the special move could land, the giant was suddenly encased in a green glow. Slowly, to the shock of the gaping crowd and heroes, he floated up a few meters, then was launched like a football into the bright sky.

All were looking around confused, wondering what on God's Earth just happened. For a couple of seconds, so did Izuku, until he quickly realized what happened after he remembered the color of the glow surrounding the villain. Oh, I can't believe it! It's her! He thought. It's-!

"TATSUMAKI, THE TORNADO OF TERROR!" The crowd interrupted. Everyone, including Izuku chanted her name over and over, much to the annoyance of the other three heroes. After all, they really didn't like the girl for her arrogant and disrespectful personality.

The strongest Esper in the world just rolled her eyes at the ease in which she vanquished the villain. Ugh. Just another waste of my time. When am I gonna get called in for a REAL threat? The short esper thought with a bored expression on her face. And when will these stupid people stop all their fuss. It's like they've never seen a hero before. But I guess since its me they're cheering for, it is a bit more understandable.

What, so now she's getting all the credit? Kamui thought in frustration of getting his win stolen, especially by someone who doesn't really care for her victory. Suddenly, Mt. Lady came running in, having heard about the villain's rampage and came prepared to make her debut with an introductory kick for the media.

"Show no fear, cause Mt. Lady is here to-!" She stopped speaking when she noticed there was no villain in sight and everyone was taking pictures of The Tornado of Terror. "So cute. So cute. So cute." A group of reporters repeating while taking pictures of Tornado's adorable, childlike physique. "Uh, hello! You got a big, mature hero over here! One who's body is all grown!" Mt. Lady said, frustrated that she was being ignored. Only Izuku and a woman holding her baby noticed her.

She's got a gigantification quirk. Better write this down. Izuku thought while getting out his notebook. The woman with her baby simply shouted, "Hey, what took you so long! The REAL hero took care of it already!" Mt. Lady looked the shouting woman with an angry expression, wanting to flick her away with her big finger, but relented both because she had a baby in her arms and because she knew it was wrong. But the temptation!

"Well, that's that. Better get home before other amateur villains do something stupid and the government needs me to help some mediocre heroes who can't do their job." Tornado said to herself before flying away.

"Tch. It's like it as simple as taking out the trash for her. She has no respect for her duty" Death Arms told Kamui annoyed. "Tell me about it." Kamui replied.

Scene 2: A grocery store

Saitama was just having one of his shopping days, but this one was better than the usual due to the great sale the store was having on noodles. Two bags for 550 yen. Can't beat that. Saitama thought. Some people were giving him curious looks for his yellow costume with red gloves and boots, but just wrote him off as some low-ranking hero who could only catch D-list villains with luck.

Suddenly, just as Saitama was about to pay for his groceries, a slime-like villain charged right into the store, surprising the shoppers and cashiers. Everyone was either ran screaming or stood still, too shocked to run. "Okay, you minimum wage jackasses, back off the registers! This is a hold up!" The Sludge villain told the cashier all the while pointing at them. The poor cashiers obeyed, and Sludge just smashed the registers and put all the money into his gooey body. "Ohhh! This is just way too easy!" He said with confidence.

"Hey, I still haven't paid." Saitama said to Sludge while walking up to him. Sludge just stared at him for five seconds, then put his arms where his stomach would be and started laughing.

"Is this some kind of joke?! What's with that stupid get up little man?" Sludge asked with a mocking smile.

"It's my hero costume stupid and you just wrecked my shopping day. I came here for the specials, and I still need to pay, so just put the registers back and go home." Saitama told him with a bored, expressionless face.

"Ha! Big talk from a fool in a clown suit! You really think you can talk to me like that and not get ripped in half? How about this, you get on your knees and beg for forgiveness, and I might decide that I don't need to use you body as a suit lightbulb head!" He declared while towering over Saitama menacingly.

The words "lightbulb head" triggered a rare and extreme sense of aggression that Saitama does not possess most of the time. People can rudely bump into him, yell at him for holding up a line, or a villain or Mysterious Being can threaten to rip his insides out, and Saitama will just go along like a regular conversation. But the one mistake no one in their right mind must ever make is make a pun or insult about Saitama's one weakness: his shiny bald head.

Putting on a serious expression and narrowing his eyes angrily, Saitama pulled his right fist back to gear up for a simple punch. "What did you just say?" He growled.

"Aww, did I hurt your little feelings bowling ball head? Well here, about I end you inner pai-"That was the last thing the monster ever said as Saitama threw fist forward into a might blow. The sludge monster could only howl in pain for a split second as he was violently dissipated into many tiny pieces that soon dried up from the sheer heat of Saitama's punch. The front area of the grocery store soon had a hole in it bigger than a school bus as a result of the punch.

"Ew, I got some of that thing on me. And I just cleaned this outfit from the last fight." Saitama complained. But he didn't have time to ponder over his filthy uniform as the store manager, a dark haired woman in her 30's, came back from her break and yelled, "AHHHH! What the hell happened to my store?!"

Saitama looked at her for a quick second with surprise and fear in his eyes before taking off faster than the speed of sound. He has to penny pinch quite a lot, so it wouldn't do for him to have to pay for damages. Man, now I can't ever go back to that store. Just my luck. He sadly thought.

Back at the store, All Might arrived just as Saitama left. "Fear not citizens! Hope is restored now that I am here!" He confidently proclaimed with his trademark smile. All Might was planning to do his own shopping when he noticed from a distance a large blast coming from the store (Saitama's punch). But he all he found was a huge hole with pieces of brittle rock-like substance all over the place. "Uhh, did I miss something?" He asked out loud, but the manager was busy complaining about insurance and having to shut her store down until the damages were repaired. While others surrounded him asking for his autograph, or questioning if he defeated the monster, All Might could overhear from the store manager. "I am gonna find that bald little punk and shove his cape down his throat! He thinks he can wreck my shop?! The nerve!"

Bald little punk with a cape? All Might thought. He would be on the look out for a bald man with a cape and seemingly great strength from this point on.

Scene 3:

Izuku was walking home from school recalling the great fight between the villain and the heroes. He enjoyed the memory so much that he pushed aside his awful day at school when all his classmates mocked him for wanting to attend U.A despite being quirkless. Though he was devastated that Katsuki destroyed his notebook out of anger that Izuku would dare to try and mock him, as Katsuki saw it, by intending to attend U.A. I can do it! One way or another, I will find a way to into that school and one day, become a great hero like All Might! I won't let anyone deter me from that dream! He thought with conviction, although he still had doubtful feelings.

Suddenly, Izuku walked by a bald man in some kind of basic and bland jumpsuit that was rubbing some kind of goo off of himself. Izuku heard the man mumbling about a "sludge thing" ruining his shopping day and getting him unofficially banned from somewhere. Worried a little about the man's health, Izuku walked back and approached him.

"Um, excuse me mister, are you okay?" Izuku asked.

The man turned around with a blank face. "Yeah, just had the only errand that I like ruined by a diarrhea monster. Nothing like a good freak attack to ruin your day. Other than that, I'm good." The man responded.

Diarrhea monster? Is he talking about a mysterious being? Only those can be classified has monsters, as opposed to people with mutation quirks. They're humans who look that way because of their natural quirks. Izuku thought.

Suddenly, Izuku thought back to what the man said. "Wait, did you say… diarrhea? H-How can there be a monster made out of, of….?" He didn't really want to finish that sentence.

"Crap?" Saitama finished as if it was nothing. "When you fight as many villains and monsters as I do, you see so many weird things, that nothing really surprises you anymore. I once took down a monster with the body of a goat and a big cartoon star for a head. It had the power to turn flies into butterflies to attack people." He recalled.

"Uhh…" Izuku didn't really know what to say about that.

"Like I said, weird." Saitama said, noticing Izuku's lack of response and confused face.

Izuku wanted to change the subject. "So, are you like, a hero?"

"Yeah, but just for fun. I go out, punch bad guys and don't really bother with getting attention. Probably why you haven't heard of me."

"Oh." Izuku replied, finding it strange that a hero wouldn't want recognition, yet found it good to hear for some reason.

Suddenly, his phone rang. Izuku got an app that alerted when whenever a villain or mysterious being would engage a hero in a fight. He pulls his phone out and reads: CHAOS DOWNTOWN! MYSTERIOUS BEING ENGAGED WITH LIGHTNING MAX, DEATH ARMS, AND SMILE MAN IN LIFE OR DEATH BATTLE!

Izuku makes a smile of excitement. Turning his head up to the man, "Excuse me sir, but I really need to go!" He starts to run back the way he came. "It was good to meet you and have a nice day!" He shouted while look back at Saitama as he ran while waving at the bald hero. Of course, he didn't notice that, in his excitement, his burnt notebook fell out.

"Likewise, kid." Saitama said while waving goodbye. Just as he was about to leave, he noticed the notebook on the ground. Uh oh, I've got a feeling he might not want to forget this. He thought while picking the notebook up. "Hey kid you forgot your-!" But it was too late, Izuku was long gone.

He sure is fast. Saitama thought. He decided to go after Izuku to return his notebook.

Next, a battle is fought, and two great men form a friendship.