Ep. 4: Flashback reveals Jūzō, Ōba, and Jin's past involving Harumi, a shokujinki, and a deadly succession duel.

4

The narrative shifts to a flashback detailing the friendship between Jūzō, Ōba, and Jin Kakinoki. After rescuing Harumi Kamitsuki from thugs, the trio invites her to reside at the Kifūken. They soon learn she is a shokujinki but agree to conceal this fact. The Kifūken head announces a duel to determine his successor, introducing the dangerous Kemonozume technique, which replaces arms with shokujinki limbs. Ōba withdraws, while Jin defeats Jūzō, who intentionally lost due to Harumi's pregnancy. Enraged by the lack of a genuine contest, Jin attempts Kemonozume and transforms into a monster, overpowering the dojo members. Jūzō requests Harumi's arms to defeat Jin, winning the ensuing battle. Meanwhile, Ōba sets the dojo ablaze. Jūzō awakens to find the dojo burning, many members dead, and Harumi deceased, with Toshihiko holding infant Kazuma. Believing he lost control and killed his wife and comrades, the story returns to the present, where an aged Jūzō encounters Harumi, who promptly kills him.