He was human once, before becoming bound as a shikigami—though not by choice. He serves as a gatekeeper in the spirit realm, and he'd actually set his sights on becoming the next Omamori-sama. The Nue had other plans, though. To prevent him from reaching that goal, the Nue essentially forced him into servitude, making him one of his shikigami instead. So he ended up trapped in a role he never wanted, serving under someone who saw him as a threat.
Content compiled by AnimeList.moe from publicly available sources.
