Mugen no Juunin: Blade of the Immortal

Blade of the Immortal (無限の住人, Mugen no Jūnin, lit. “the inhabitant of infinity”) is an anime series based on the manga series created by Hiroaki Samura. The series is set in Japan during the mid-Tokugawa Shogunate period and follows the cursed samurai Manji, who has to kill 1000 evil men in order to regain his mortality. Wikipedia