The series focuses on Aya Mikage, who learns on her sixteenth birthday that she is the reincarnation of an ancient and supremely powerful celestial maiden or angel ("tennyo") named Ceres, and her twin brother Aki the reincarnation of Ceres' former husband, Mikagi, the progenitor of the Mikage family, who had stolen Ceres' robe. Ceres' spirit begins manifesting in Aya, and to save her brother she must find Ceres' long-lost , while avoiding being killed or captured by family members who want to use Ceres's supreme celestial abilities for their own personal gain.