Plot This series about a normal teenage girl named Mikage Aya. Well, that is until we find out that she's actually abnormal. Aya has just turned 16 and her parents are intent on taking her to her grandfather's house to throw her a party. When they get there, though, Aya isn't exactly going to be digging into any cake or opening presents. When she becomes extremely frightened or angry she morphs into this being, whose name is Ceres.
Ceres is very powerful and can do large amounts of damage.
Due to this condition, Aki's granddad also sends out a hitman named Tooya. But Tooya has been told by Aya's cousin, Kagami, not to hurt her but to watch her and study her powers. More characters such as Aogiri Suzumi and Yuuhi appear to help her understand more about herself, Ceres, and the power she has. Yuuhi is Aogiri's brother in-law, just so you know. The story isn't exactly unique, but it's very interesting.