Yûhi, a relatively popular guy at his school, has his life interrupted by the ominous premonition of his beautiful sister-in-law, Suzumi. She sends him to rescue spunky Aya Mikage, who is under a death sentence by her own family! Suzumi relegates Yûhi to protect the high-spirited coed, but he doesn't know that two personalities dwell within Aya's body - herself and the legendary celestial maiden, Ceres. Yûhi complains about Aya all the time, but gets jealous when the handsome mystery man Tôya is around. Could it be that he actually has feelings for Aya?