Having left for Kaga in pursuit of Kagehisa, a collapsed Rin is rescued by the very same Kagehisa. Then, having to cooperate with Kagehisa who is pursued by the Shingoto-ryu, Rin starts to see Kagehisa, her enemy, as a human being.

The Ittou-ryu had its members slaughtered by the shogunate. Kagehisa gathers the remaining members of Ittou-ryu in secrecy, and plots revenge against the shogunate. Manji is invited to the Mugai-ryu by Giichi, but he refuses, and they clash swords. Giichi's weapon breaks, so a truce is called. Manji decides to go meet the head of the Mugai-ryu, Habaki.

Ever since the Dewanosuke incident, Burando kept making blunders. He is finally thrown in solitary confinement by Habaki, and goes insane. But as a result of his madness, Burando grasps something important about the immortality experiments: That humans are essentially otters. Meanwhile, Rin and Doua resolve to infiltrate Edo Castle to rescue the surrounded Manji and Isaku.

Arashino, Hasshuu, and Murasaki of the Rokki-dan act as the vanguard in the clash with the Ittou-ryu. The crucial Abayama manages to escape with the help of his followers. But then he hast to confront Giichi and Hyakurin, who pursued Abayama to assist Habaki.