Daikaku lives in his reclusive hideaway, disowned after his father was taken over by evil spirits. His sword grown dull by memories of bygone days, he has been driven to the very brink of despair...

The year is 1458. A child is born in the village of Otsuka, in Musashi Province. His name is Shino Inuzuka. After coming of age, he is entrusted with a legendary sword, the Murasame, by his father Bansaku. Shino's father, however, commits hara-kiri after losing face when his brother-in-law, Hikiroku Otsuka, tries to trick him into giving up the sword, Then Shino, devastated by his father's death, somehow comes into possession of a small bead, On this strange bead, the Chinese character ""KO"", symbolizing filial devotion mysteriously appears.

Sosuke becomes an assassin after being ordered by Kamezasa to kill Shino. The two warriors, however, soon realize the extent to which fate has connected them, and make a pledge of brotherhood. As for Hamaji, she learns that her hand in marriage has been promised to the jindai, Higami Kyuroku. Deeply in love with Shino and despondent over this news, Hamaji decides to kill herself, but is saved at the last minute by Samojiro Aboshi, who later reveals to her his true nature as an evil sorcerer and sets upon Hamaji himself. Hamaji's subsequent rescuer turns out to be her long lost brother, Dosetsu Inuyama, from whom she was separated at birth.