Zan Kokku is the eldest of the Makai Zan Brothers, a trio who collectively served as three of Doakudar's Four Heavenly Kings ruling Soukaizan's seventh floor. As top enforcers in Doakudar's army, the Zan Brothers functioned as Co-Dragons. They maintained a rivalrous dynamic with the fourth Heavenly King, Don Goro, who mentored Toraoh, reflecting internal tensions within Doakudar's leadership. After protagonist Wataru restored Soukaizan's seventh tier, the effects reversed the corruption affecting its inhabitants. This restored Zan Kokku and his brothers to their original, uncorrupted states. Don Goro, previously killed by Doakudar, was simultaneously revived and purified alongside them. The narrative does not elaborate on Zan Kokku's specific actions, mecha, or further character development beyond this restoration across subsequent series, films, or spin-offs.