In an effort to save the universe, Saitama punches God in the face in the non-canonical One-Punch Man: The Fight of Gods, a fan-made comic based on the popular anime, manga and webcomic. Created by the Hong Kong-based artist and author Cminglap, The Fight of Gods follows Saitama and the anime's cast in a ferocious battle with a being known as God, ultimately leading to a one-on-one —and somewhat blasphemous — intergalactic showdown.
Source：https://www.cbr.com/one-punch-man-vs-god-fan-manga/
