Ceres was a tennyo—a celestial maiden—who descended from the heavens to bathe in a stream. She placed her hagoromo, or feathered robe, on a nearby tree; that robe was her means of returning to the sky. However, a man stole it and forced her to become his wife, giving rise to a family line mingling human and tennyo blood.
In the present day, Aya Mikage is a descendant of Ceres and carries a significant amount of tennyo blood. On her sixteenth birthday, she and her twin brother Aki are given a party. But during this "party," Aya's grandfather intends to kill her: unlike others in the family, she possesses tennyo powers and can actually transform into Ceres herself—and destroy the Mikage family. Yet Aya is able to revert, so this transformation occurs frequently.
With her protector Yuuhi at her side, Aya must control Ceres and prevent her from reemerging. However, her relationship with a former employee of her wicked grandfather may prove to be a distraction.