One fateful day, all of humanity was petrified by a blinding flash of light. After several millennia, high schooler Taiju awakens and finds himself lost in a world of statues. However, he's not alone! His science-loving friend Senku's been up and running for a few months and he's got a grand plan in mind, to kickstart civilization with the power of science!

A samurai lord has bartered away his newborn son's organs to forty-eight demons in exchange for dominance on the battlefield. Yet, the abandoned infant survives thanks to a medicine man who equips him with primitive prosthetics—lethal ones with which the wronged son will use to hunt down the multitude of demons to reclaim his body one piece at a time, before confronting his father. On his journeys the young hero encounters an orphan who claims to be the greatest thief in Japan.