Sesshomaru travels to Bokusen'on, a tree y?kai responsible for the construction of the powerful inherited sheaths, who reveals the truth about InuYasha's demonic transformation. Elsewhere, InuYasha and his companions are led to a group of bandits who are terrorizing a nearby village. InuYasha and Miroku encounter a moth y?kai named Gatenmaru, who traps them in a venomous cocoon, intending to own the Tetsusaiga. However, InuYasha begins to alter to his y?kai state, once separated from the sword that seals his demonic blood.