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.

Struggling manga author Satoru Fujinuma is beset by his fear to express himself. However, he has a supernatural ability of being forced to prevent deaths and catastrophes by being sent back in time before the incident occurred, repeating time until the accident is prevented. One day, he gets involved in an accident that has him framed as a murderer. Desperate to save the victim, he sends himself back in time only to find himself as a grade-schooler one month before fellow classmate Kayo Hinazuki went missing. Satoru now embarks on a new quest: to save Kayo and solve the mystery behind her disappearance.