Ep. 4: Yataro locates the Obsidian Goddess within the Uesugi army while Musashi confronts the traitorous Michiru.

4

Yataro informs Seiroku that he found the Obsidian Goddess inside the Uesugi army, prompting a plan where Seiroku and Shiro attack the Bushi while Yataro secures the prize. Yataro reveals a daughter discovered the goddess. Meanwhile, Michiru frees Musashi, but Akihiro threatens him, suspecting Musashi's Shimazu ties. Akihiro recalls their father favoring a concubine's son and plans to kill them during the Awaji island operation. Three oni arrive to help their sister Michiru retrieve the goddess, suspecting she acts as a spy. Michiru confesses her mission to Musashi, who doubts her betrayal. Her father appears, urging her to finish the task. Minami forces Michiru toward Musashi, but he dodges and cuts her fingers. Michiru protects Musashi from the oni, who regenerate. Kuroko, Kanetatsu, and others arrive to save her. Kanetatsu kills most oni, but Minami and Iwanami merge after devouring their kin. Tatsuomi Uesugi arrives, using yellow Kitetsu Blades to enhance his men's physical traits. The Uesugi Bushi overpower the oni. Minami attacks Tatsuomi but is restrained by their bond and killed by Kanetatsu. Tatsuomi questions the oni's entry, but Shiro admits he let them in with his blade.