Three sisters - Sachi, Yoshino and Chika - live together in a large house in the city of Kamakura. When their father - absent from the family home for the last 15 years - dies, they travel to the countryside for his funeral, and meet their shy teenage half-sister. Bonding quickly with the orphaned Suzu, they invite her to live with them. Suzu eagerly agrees, and a new life of joyful discovery begins for the four siblings... The film is based on the manga series Umimachi Diary by Akimi Yoshida.