"Saiai no Kodomo" is a novel set among classmates at the upper division of private Tamamo Academy, where Hinatsu, Mashio, and Utsuho are watched as a self-made "family." The balance among two girls who appear almost like a married couple and a third who joins them like a child is depicted as a relationship that cannot be reduced to romance, friendship, or family.

A story of relationships that resist naming, told through classmates watching a makeshift family of three high school girls.