Mugen no Juunin: Immortal
English title: Blade of the Immortal
Japanese title: 無限の住人-IMMORTAL-
Type: ONA
Source: Manga
Episodes: 24
Status: Finished Airing
Aired: Oct 10, 2019 to Mar 26, 2020
Duration: 23 min per ep
Rating: R - 17+ (violence & profanity)
Studios: LIDENFILMS
Producers: Nihon Ad Systems, Mainichi Broadcasting System, Pony Canyon, Kodansha
Licensors: Sentai Filmworks
Genres: Action, Adventure, Drama, Supernatural
Themes: Gore, Historical, Martial Arts, Samurai
Demographics: Seinen

Manji is an infamous swordsman in feudal Japan who is known as the "Hundred Man Killer," as he has killed one hundred innocent men. However, there is something far more frightening than his ominous reputation: the fact that he is immortal. This is the handiwork of eight-hundred-year-old nun Yaobikuni, who placed bloodworms capable of healing almost any wound in Manji's body.

To atone for his crimes, Manji resolves to kill one thousand evil men. Yaobikuni agrees to this proposal, saying that if he succeeds, she will undo his curse of immortality. Soon after this promise, Manji meets Rin Asano, a 16-year-old girl who requests Manji's assistance in killing those who slaughtered her parents.

Initially reluctant, Manji refuses Rin's desperate plea. However, owing to her evident lack of strength, Manji changes his mind and agrees to protect Rin for four years. With this partnership set in stone, the two embark on a perilous journey of bloodshed, vengeance, and redemption, each to fulfill their own life's cause.

[Written by MAL Rewrite]