The Description:
 Teenager Aya Mikage and her twin brother Aki are called to their grandfather's home for a special celebration for their sixteenth birthday. Instead they find themselves the victims of an ancient family ritual. Aya is found to be the reincarnation of a celestial maiden and upon reaching the age of sixteen her body is able to bring forth a powerful, celestial maiden called Ceres. When she transforms into Ceres, Aya obtains supernatural powers and often forgets what she has done during the transformation, resulting in a double personality. According to the legend, if left to live, the reincarnation of Ceres will bring ruin upon the Mikage family. Aya quickly finds herself assigned a death penalty by her own family. However, she is saved by Suzumi Aogiri, another celestial maiden descendant, from Kansai and Suzumi's brother-in-law, Yūhi. They take Aya into their home after she is forced to run from the Mikage.
 Events escalate as Aya struggles to control Ceres and her brother is taken over the soul of "Mikagi", the ancestor of the Mikage family who stole Ceres' celestial robe preventing her return to heaven. Aya must also wrestle with affection for Toya, a Mikage employee with no memory of his own past. He is assigned to protect Aki and observe Aya by the leader of the C-project (celestial project). As he carries out his mission, he begins to develop feelings for Aya...(the material was taken from wikipedia.org)