Hey everyone and welcome to My Hero Fighterz. A three-way crossover set in One Punch Man world. Now before we begin I want to go over a few things first, yes this is set in Universe 6 Earth and yes this is a Goku story replacing Saitama. While that is the idea I'll try to focus on other characters as well. Next I always found it weird that U6 saiyans don't have tails so I'm going to give some of them tails which will be explain in this chapter and if you want me to give Caulifla and any other saiyan a tail let me know. The Super Saiyan legend will also be there because U6 saiyan can transform. And yes Quirks will be a thing.

Yes some heroes will learn ki but not all and not right now. And one more thing I will replace some OPM characters with My Hero Academia, like replacing King with All-Might which will also change the Ranks of almost everyone. Alright lets begin.

Chapter 1: Kakarot's New Beginning. The Monkey Hero: Son Goku!

Planet Sadala

Bardock was the most happiest saiyan on the planet. So happy he almost destoryed his home. His wife Gine just gave birth to his second son Kakarot. An 7-year old Raditz just looked at his brother in awe then said, "he is so small."

"Yes most babies are," Gine said with a bright smile.

"Hey why does he have a tail?" Raditz ask seeing the most oddest thing there.

Bardock just lightly less surprise notice too and just smiled even more. The doctor there said not surprise at all "well there is a reason for that young man, you see saiyans many years ago use to have tails but as time passes we evolve and not have the need for a tail but there are a few who are born with tails, granting them the power to transform into a Oozaru under a full moon. They could have more potential then the average saiyan but requires much more training because they can't control the Oozaru form well and must learn to use it. I suggest keeping your boy inside during the Moon Festival."

They all nodded and Raditz hearing that his little brother could be stronger then him he vows that he will become someone strong so that his parents will be proud of him. For now they all went home and celebrate. Little did they know this was the beginning of a new adventure.

Planet Earth

25 Years later

In City A all seem peaceful, until a huge explosion causing a building to collapse. People running in fear at the sight of thmonster attacking. A little girl was crying out for her parents. Most of the heroes have fallen except Rumi Usagiyama AKA Miruko who was struggling to get up. The monster just looked at the girl with an evil grin as he went to attack her. But she just suddenly vanish leaving Rumi and the monster confused. The monster then turn around to see a man with spikey hair and a brown tail wearing a orange gi. He had rescued the girl as the monster clench his fist in anger. He looked at the man and said, "your pretty fast for a human."

The man just smile making the monster more angry. Miruko looked confused and worried. She thought the man was in over his head and tried to get back up but couldn't. She only hope the man could hold off the monster long enough for an S-Class hero to arrive. She curse herself quietly for being too weak.

The man looked at the monster and said, "my hero name is Son Goku what's your name?"

The monster blink in surprise and said, "I am Vaccine Man, I was created by Mother Earth herself to eliminate mankind."

"Why," Goku simply ask setting the girl down in a safe location.

"Because humans like you are a disease eating away the planet's life, and because of that I was born," Vaccine Man said.

Goku just gave a disappointing look, "true humans can be terrible people but it's not like your any better causing the same kind of destruction."

Vaccine Man was now furious, being compared to humans was an insult and he would have none of that. "You say that but you will come to realize that I AM SUPERIOR THAN YOU," Vaccine Man began to transform and charge at Goku.

Goku stayed calm as he began to charge his attack. "KA... ME... HA... ME... HA!" Goku fired a blue beam at Vaccine Man killing him.

Rumi stared in shock before passing out. Goku let out a sigh, "well that was boring, I got too carried away thinking he was a rouge Namekian or something, oh well best to head home."

Goku or Kakarot as his close friends and family calls him, began to recall what brought him to Earth in the first place.

Planet Sadala three months ago...

It was a normal day on Sadala, Kakarot was training on a remote island while an old man was sitting in a chair observing him. They both notice a ship coming their way and immediately got ready to greet them. The ship land and out came a tall man with long hair. Kakarot recognize the man as Raditz and went up to greet him. "Hey bro it's been so long, what brings you," Kakarot ask giving his brother a fist bump.

Raditz returning the fist bump then said, "well brother I'm actually here for a mission that might interest you."

Raditz explain that the Sadala army found a new planet called Earth and they want invite the inhabitants to be part of the Galactic Alliance because they have strange and useful powers. He went on saying that they need someone to join their Hero Association to prove that 'aliens' can be trustworthy. "As captain of the Elite Guard I suggested you because your not part of the army and your one of the strongest saiyans on the planet," Raditz finished.

Kakarot thought for minute. On one hand, he thought the people on Earth would be weak and wouldn't give him a challenge, on the other hand hearing that these people have strange powers might be fun to fight. The old man name Master Roshi said, "Kakarot I think you should go to Earth, it is a great learning opportunity for you and explore beyond your planet, and besides I don't believe I have anymore to teach you."

Kakarot just looked at his master confused. Roshi continued, "over the past 10 years you have grown much more powerful than I could ever be, and your skills have improve greatly but if you want a shot a the Galactic Warrior Tournament you need to understand how to fight tricky opponents and Earth seems like a good place to start."

Kakarot did like the idea of getting stronger but he is wondering something. "Why do you think I would be best for the job," he asked Raditz.

"Well your the best fighter on the planet and won many Sadala Tournaments over the years, so you represent the saiyans the most. As a bonus your not part of the army meaning you have more free time on your hands and you would look normal despite having a tail, the Hero Association doesn't want civilians to know about us yet," Raditz said.

Kakarot gave it more thought. He then agrees, under one condition, "I want bring one of my friends along, it be pretty boring if it was just me."

Raditz asked who as Kakarot smiled.

Earth few days after Vaccine Man's attack...

Kakarot or 'Goku' as the people of Earth call him, began thinking about his time here, in a small apartment in Z-City. He liked the idea of being named after one of Earth's legends, thinking it sounded right to him. He fought all manner of monsters and villians, many were skilled but none were at his level. He was starting to get bored and sometimes wanted to test out the S-Class heroes but do to him being a B-Class he wasn't allowed to meet them yet. Of course they know about Goku being an alien and saw that his physical test was off the charts but the written test put him in B-Class. That and the number 1 A-Class Sweet Mask didn't like the idea of an alien being a hero and try to dismiss the idea of working with them but the higher ups wanted to be part of the Galactic Alliance to gain more resources and even the S-Class heroes agree because they want strong allies to help them in times of crisis or at least most of them do.

Goku doesn't mind, it gives him a goal to work towards but he is lonely, he hope his friend would show up soon. He hears a knock on the door and wonder who could that be. When Goku answered, he was surprise to see who it is.

Me: Done now before you all say anything I want to point this out now, I believe that Goku x Caulifla could be a thing and I like the idea but I also like Chi-Chi with Goku. I also think Chi-Chi might like Caulifla because of how similar she is to Goku and how she helps and protects Kale, and Caulifla might respect Chi-Chi because she is not afraid to stand up and put others in their place. I can list good reasons why these two would be friends. I'm saying this because I might make this a Goku harem story later on.

In terms of power this Goku is as strong as Buu Saga Goku. And if you think I'm making Goku weak I don't think I am. U6 Saiyans are born stronger then U7 and this is a few years before Super so they will get stronger over time. And besides Goku became strong by going on an adventure and learn. This Goku is also smarter but with the same personality and carefree attitude.

Now why am I using the One Punch Man world as a start, well I don't know much about U6 beside the people that live there. You can do whatever you want with U6 because it's a blank slate right now. I need a start and OPM could work. I'm also throwing in My Hero because I can and would make this so much more interesting.

And now Saitama he will be in this and as the Number 1 S-Class hero, but not much will change because of that. He is powerful I will admit, but how strong is he? I think he is as strong as final form Frieza during the Namek Sage. My reason, well Saitama can win fights with little to no effort with a single punch. Frieza can destroy planets in his first form no problem. Both of them know how to hold back in different ways. Now if you don't agree with me that's fine.

Now here are my questions for you. How will U7 change without Goku? Would you like me to add other U7 characters? Should there be Dragon Balls to find? And would you like me to use Broly in some way? Well this is Renegade100 signing off.