One Punch, Combat King

Sinopsis

William — known in the fighting world as The Reaper and the most feared fighter alive — vanishes after his coach is murdered for refusing to fix a match. He resurfaces in silence, working as a janitor at his late coach's gym, watching over the coach's daughter, Elena, from the shadows, waiting for revenge. When the criminal syndicate comes back, trying to shut the gym down and threaten Elena, The Reaper steps back into the light.