Tokyo Revengers: From Assassin to Hero

A trained assassin dies due to an explosion, but for some reason ends up reincarnated in the body of a young Japanese 26 years old, everything happened normally for a while, he was already adapting to his new life, but then he discovers that the previous girlfriend of the owner of the body died because of a certain gang, he simply regrets and continues with his life, but in an accident falls to the local train tracks and is about to die, resigned closes his eyes waiting for his death, but again instead of dying he discovers that he is 12 years in the past. First story I have written, I hope you like it