In the "Japanese-style fantasy battle" story, mechanical sparrows chase after the girl Nerine on a moonlit night, but a boy and a girl save her. The boy is the older brother Akahiko, who is sullen, stingy, and polite to a fault. The girl is the energetic younger sister Yukio, who can manipulate snow. The pair are supernatural problem-solvers for hire, doing anything from intimidation to exorcisms as the Nihonmatsu siblings.