[Anime]Blade of the Immortal (Mugen no Juunin)

Blade of the Immortal follows the deeds of Manji, a skilled samurai who has a decisive advantage: no wound can kill him, except for a rare poison. In the past, his criminal actions led to the death of 100 other samurai (including his sister's husband). He becomes immortal at the hand of an 800-year-old nun named Yaobikuni, and is compelled by the death of his sister to accept the quest that will end his agelessness. He has vowed to make amends by killing 1000 evil men, and until he does Manji will be kept alive by "sacred bloodworms", remarkable creatures that allow him to survive nearly any injury and reattach severed limbs even after hours of separation. They work by sacrificing themselves to seal the wound - they're worms that were bred to be as close in their chemical and physical make-up to humans as you can get without being human. They cannot handle regrowth on a large scale, but, for example, can reattach a severed limb or seal a hole in the brain.

Manji crosses paths with a young girl named Asano Rin and promises to help her avenge her parents, who were killed by a cadre of master swordsmen led by Anotsu Kagehisa. Anotsu killed Rin's father and his entire dojo, making them a family of outcasts. Anotsu's quest is to gather other outcasts and form an extremely powerful new dojo, the Itto-ryu (a school teaching any technique that wins, no matter how exotic or underhanded), and has started taking over and destroying other dojos.

In addition, another group calling itself the Mugai-ryu has emerged, in opposition to the Itto-ryu. Its true leadership and motives are initially a mystery, but its methods (any tactics that leads to victory) resemble those of the Itto-ryu. They try to enlist Manji's help as they seem to want the same thing. Eventually Manji joins but quickly pulls out after he finds out a member, Shira, is way too sadistic for his tastes. After a while Manji finally discovers that the Mugai-ryu work for the government. They are all death row inmates who are allowed to live only if they serve the shogunate . While Manji and Shira quickly grow to hate each other, after Shira runs off, Manji remains on friendly terms with the other members of the group.

In a broader context, the series covers the effects of death and the consequences of not being able to die, as well as the meanings behind living. Most of the principal characters have some sort of purpose which they inexplicably discover through the events that transpire.
This story has the part which was created by referencing Wikipedia, so the licence of GFDL is applied to this story.

Hiroaki Samura Koudansha Monthly Afternoon
Kouichi Mashimo
Hiroyuki Kawasaki
Ko Ohtani Toru Nakano
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Tomokazu Seki Rina Satou
Nojima Hirofumi Masashi Ebara Kazuya Nakai
Katsuyuki Konishi Mamiko Noto Daisuke Namikawa
Shinichiro Miki Megumi toyoguti Toshiyuki Morikawa
Utida Yuya Takayuki Sugo Toshihoko seki
Hisako Kyouda Maaya Sakamoto Ryoko Shiraishi
Wataru Hatano Kouichi Sakaguchi Tokuyoshi Kawashima Takaya Kuroda