In feudal Japan, the infamous swordsman Manji, dubbed the 'Hundred Man Killer,' carries the burden of immortality bestowed upon him by a centuries-old nun. Seeking to lift this curse, he vows to eliminate one thousand wicked individuals to redeem his past sins. When he crosses paths with Rin Asano, a determined young woman seeking vengeance for her parents' murder, Manji initially hesitates but eventually agrees to aid her. Together, they forge a reluctant partnership filled with blood-soaked battles, seeking both retribution and absolution on their intertwined paths of destiny.