Human Z12427 was the last human in the robot body, fighting in the arena for the robot's fun if they can have it. His memories about his name have been deleted long ago, decades, if not centuries. Humanity had long been conquered by robots, only small group are surviving and hiding. Z12427 fought in the arena, but one day just ended his life, but suddenly find himself in a strange place with a lot of monsters, and all reviving monster, who's claiming himself as Immortal Demon lord. Will he survive? And what's more important, will he find a place for himself?