今日のケルベロス

As a child, Chiaki Mikado lost a piece of his soul to the bite of a strange three-headed dog, and he has faked every smile since, unable to feel real joy. Years later his father ships him a box from Greece. Inside is a girl who shifts between three forms, Kuro, Shirogane and Roze, and who turns out to be Cerberus, guardian of the gates of Hades and the very creature that took the piece. She moves in meaning to make him smile again and to guard him, since what is missing draws wandering spirits and fiends his way.