Izuku Midoriya: The Saiyan Vigilante

Prologue

Tartarus Prison, a federal prison located on an isolated artificial island in the middle of the Indian Ocean and accessible only by aircraft and spans over 500 meters down.

A powerful fortress, it's main objective is to ascertain that most vile, violent, vulgar and obscene villains never escape. Criminals that can never reform are sent to its deepest depths.

The entire prison had soundproof cells and impenetrable walls so that it can further decrease the villains' hopes of escape.

The guards were doing their last round of scouring the perimeter before the warden called lights out.

Right now, a villain named Toxic Chainsaw was slamming his fist against the powerful glass and nullified any sound.

His recent crime was attacking a mall and taking someone hostage. That hostage being the daughter of the newly wealthiest family in Japan, Momo Yaoyorozu and forcefully undressed her.

The public thanked All Might for the saving of countless civilians. But Toxic Chainsaw knew that All Might didn't save her. It was someone else, but he didn't care who. He wanted vengeance. To cut down the Hero Society.

TC: JUST WAIT!! I WILL BUST OUT OF HERE AND MAKE YOUR LIVES A LIVING HELL!! YOU'LL PAY, ALL MIGHT!! I SWEAR IT!

A echoey deep voice spoke

???: How very naive. . . .

The villain turned around and deep within that darkness peering, a figure stood, eyes glowing red. Footsteps began and as he revealed himself, the villain's eyes turned rage into unimaginable horror.

TC: Y-y-you!!!

The mysterious shape walked closer.

TC: Y-y-you've got it all wrong, man!!!! Please I'm serious, I really can change!!

The figure grabbed him by the neck and raised him high.

???: How many people begged you for mercy before you cut them down? How many wives have you turned into widows? How many beloved mothers did you steal from children? How many futures did you steal?  Against my better judgement, I'll let you live, but know this. I can come kill you at any time. You're not safe. Not anymore. Nevermore.

TC: Oh, God. What the hell are you?

???: The name is Deku. Remember it.

The mystery man then proceeded to hit him on the side of the head, rendering him unconscious.

The enigma dropped him and he then vanished into thin air and left a newly traumatized Toxic Chainsaw.

The next morning the guards were trying so hard to make him leave his cell.

TC: HE'S OUT TO GET US!! ALL OF US!! WE ARE ALL GONERS!!

The guards then put him in a straitjacket and sent him to the upper levels which was mostly for rehabilitation purposes and recreational programs.

The guards were wondering about what he said.

Guard 1: One day in here and he's already gone insane?

Guard 2: Didn't his little warning freak you out just a bit. I mean, who's out to get us?

Guard 1: I don't know and I really don't care. Now, come on. We've got a prison to run.

While the first guard moved in without hesitation, the other moved with caution, a sinking feeling in his stomach.

The vigilante returned home and dressed in his civilian uniform and painfully went to sleep. The next day everyone, hero and villain, heard the news of Toxic Chainsaw's newly deteriorated mental state. They called this man a monster, a ruthless heathen, a disgusting devil.