USJ

After so many abuse, neglect, torment, bullying and pain. Izuku Midoriya, formerly Yagi, find a weird orange dog with a chainsaw on his head. It was a devil. Izuku helped the dog and they begin friends.
At the age of 12, Pochita died and begin Izuku hearth. Soon a beautiful woman asked him to work for her.
He immediately accepted.

Now Izuku Midoriya has 2 tasks.

To find his dad(Hisashi doesn't know about Izuku)
To kill the evil devils as The Chainsaw Man.