Blade of the Immortal

Manji, a swordsman known as the "Hundred Man Killer," has lived an immortal life due to the intervention of Yaobikuni, an 800-year-old nun who implanted bloodworms in his body. To atone for his past crimes and reverse his immortality, Manji has set a goal of killing 1000 evil men. While traveling, Manji meets Rin Asano, a 16-year-old girl seeking revenge against those who murdered her parents. Manji agrees to protect Rin for four years, and together they navigate a path of violence and redemption.