Manji is an immortal swordsman who has been cursed with eternal life. He longs for death because of the violence he has caused. Despite his lack of abilities other than killing, Manji devises a plan to regain mortality - he will kill one hundred evil men for every good man he has killed. The witch who afflicted him agrees and sets him on this path. Along his journey, Manji meets Rin, a young girl seeking vengeance against the sword school that killed her family. Together, they travel, facing numerous enemies as they search for peace. Throughout their journey, Rin and Manji must learn to control their desire for revenge and live their lives without being consumed by it.
Mugen no Juunin won the Excellence Prize at the Japan Media Arts Festival in 1997.The series was published in English by Dark Horse Comics as Blade of the Immortal in 31 volumes from March 1, 1997 to April 1, 2015. The release featured the unusual method of cutting out and rearranging panels, which was done so to have the series read left to right while still appealing to Hiroaki Samuras request of not flipping the pages. The series was first released in monthly comics issues from June 1, 1996 to November 14, 2007 but was stopped after 131 issues. Dark Horse has been republishing the series in 3-in-1 omnibuses since January 10, 2017. The final omnibus will contain the novel Blade of the Immortal: Legend of the Sword Demon. The series has also been published in Brazilian Portuguese by Jbc in a 2-in-1 edition since December 2015.