Tập 4: Hồi tưởng tiết lộ quá khứ của Jūzō, Ōba và Jin liên quan đến Harumi, một shokujinki, và một cuộc đấu kế vị đẫm máu.

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The story goes on a flashback, depicting Jūzō, Ōba, and Jin Kakinoki's friendship. The three rescue the mysterious Harumi Kamitsuki after from a group of thugs and bring her to live in the Kifūken. They eventually discover that Harumi is a shokujinki, but agree to keep it a secret. Eventually the head of the Kifūken announces that he wants one of them to be his successor and will have a duel to decide who is most fit. He also reveals the technique called "Kemonozume"; that involves cutting off one's own arms and replacing it with shokujinki's limbs. If not strong-willed enough, the Kemonozume will make the host a monster. Ōba backs out of the duel, and Jin wins the match with Jūzō. The latter throws the match on purpose because of Harumi's pregnancy with his child. Jin leaves angry that he could not have the real duel he wanted. This led Jin to try out the Kemonozume method, and he became a monster and overpowered the Kifūken members. With no other choice, Jūzō asks Harumi to give him her arms so he can defeat Jin. Both Jin and Jūzō fight as shokujinki, and Jūzō wins the battle. Meanwhile, Ōba puts fire in the dojo. Jūzō awakes to the dojo in flames, many members dead, and finds Harumi dead; along with Toshihiko holding an infant Kazuma. With Jin apparently dead, he strongly believes he lost control and killed his own wife and members. The episode ends in the present time with an aged-old Jūzō apparently seeing Harumi, who quickly turns and kills him. (Source: Wikipedia)