A group of boys and girls, twelve in total, gather at an abandoned hospital to die for various different reasons. There, they find the body of a dead boy. The group of twelve attempt to find the person who killed the boy. During their search, the reasons why they want to die are revealed.

Tenmasou is a long-established inn atop a mountain overlooking the sea, in a town called Mitsuse that exists between heaven and earth. The inn is run by Nozomi Tenma, the proprietress. Her younger sister Kanae works as a dolphin trainer. Their mother Keiko is the inn's elder proprietress, who is still resentful of her ex-husband that deserted his wife and family.

A sect is threatened to fall apart, when its leader, a young Korean woman, develops doubts regarding her alleged psychic powers.