Doomsday: My Shadows Are All Great Heroes

Reborn for a second time, Jiang Chen returns to the first day of the apocalypse. He saves his younger sister and awakens the ability [Shadow Fiend] (his shadow mutates into a demon with the potential to awaken all kinds of abilities. It exists independently and grows stronger as its mutation deepens. Later on, he can activate multiple demons), then rescues the girlfriend he had in his previous life. After that, he begins a leisurely life as the hidden power behind the apocalypse.