Three sisters live together in their late grandmother's house in the city of Kamakura. They have lived together since their dad left home for another woman and their mum imitated her husband by running off with another man. Sachi, 29, the oldest Koda sister, a nurse at the local hospital, acts as a substitute mother to Yoshino, 22, and Chika, 19. One day, the threesome learns of the death of their "traitor" father and it is only halfheartedly that they go to his funeral. But in Yamagata something unexpected happens: they meet their half-sister Suzu, 13, there and immediately fall for the spell of this exquisite young creature. Sensing that Yoko, her father's widow, will not be a fit guardian, Sachi invites Suzu to move in with them.