On their way back to Owari, and the duo find the next sword Biyorigō is embedded in a mechanical doll inhabiting an abandoned lake. Meanwhile, Umigame Maniwa encounters Emonzaemon along the way. He reveals that the Maniwa wiped out his ancestors, the Aioi ninja corps, and summarily kills Umigame. Togame gathers information and attempts to capture the mechanical doll by setting a trap which fails so she has Shichika trick it into revealing all of its techniques by carrying out a series of attacks...