Return of a King

Muzan Kibutsugi was dead, and would never reincarnate due to his status as a Demon and because of his actions. Or at least, that was what everyone thought. While Muzan would never get the chance to truly live again, he could always make sure his legacy carried on in an event of a rebirth... (OP!Izuku, MorallyGrey!Izuku, Demon!Izuku, HeavyCanonDivergence)