Three Koda sisters, 29-year-old Sachi, 22-year-old Yoshino, and 19-year-old Chika live at their grandmother's home in Kamakura, Japan. When the Koda sisters were young, their parents divorced and they were abandoned. Not having seen their father in 15 years, they receive news of his death. Sachi asks her sisters, Yoshino and Chika, to attend the funeral where they meet 13-year-old Asano Suzu, their half-sister. Yoshino is aware that her father's widow, Yoko, is not Suzu's real mother and finds her to be unfit as a guardian. Concerned for Suzu's well-being, Sachi attends the funeral and invites Suzu to live with them, Suzu gladly accepts.
