Mokuzu was a simple groundskeeper at the temple where the onmyodo studied. He lusted for power and begged anyone he met to teach him their skills. Only Shiranui relented and kept the man alive for centuries as an underling. It was Mokuzu that threw Haimaru into the kodoku pit that transformed the cat into Byoki.
(Source: furinkan.com)
Content compiled by AnimeList.moe from publicly available sources.
