Maryoku 9999-man: Zen Zokusei Tsukai no Dai Kenja

All over the world, Monsters suddenly began appearing. The only person who could save humanity from “The Calamity” was “The Great Sage”, Ichikami Atsumu. Despite being satisfied in his death, he was reincarnated into the body of a boy who was bullied into killing himself, Kusanagi Minato.
Atsumu, waking up in a Japan fifty years into the futur...