He is the head of the Zaku Clan, and once fought alongside the Shodai Gundam Daishogun against the incarnation of darkness, Kuromajin, and was best friends with Sho Gundam. Suddenly, under the mysterious ruler, Yami Shogun, he formed the Dark Army and challenged the Gundam Army to a fight. At first, the existence of Yami Shogun itself was a mystery, but after intelligence was gathered by spies, it was revealed that Zakuto, clad in the "Armor of Dark", was Yami Shogun himself, and that Zakuto himself was merely being controlled by the "Armor of Dark". Even though he was controlled by the "Armor of Dark", Zakuto never lost his integrity even in his evil deeds, but once the "Armor of Dark" was put on, he became a cold-hearted, ruthless Yami Shogun. Yami Koutei used the "Armor of Dark" to pit those who once opposed him against each other, a despicable strategy.