There are three sisters: 29-year-old Sachi Kouda, 22-year-old Yoshino Kouda and 19-year-old Chika Kouda. They live at a house in Kamakura, Japanese. Their house was left by their grandmother. One day, they receive news of their father's death. When the sisters were young, their parents divorced and their father left them. They haven't seen their father in 15 years. Upon hearing the news on their father's death, the younger sisters, Yoshino and Chika, do not feel anything, because they hardly have any memories of him. Oldest sister Sachi is different. She can't forgive her father, because she remembers him clearly. Sachi decides not to attend her father's funeral and asks her two younger sisters to attend. At the funeral, the two younger sisters meet their stepsister Suzu Asano. She is a middle school student. Yoshino is aware that her father's wife is not Suzu's real mother and Suzu's future is uncertain. Yoshino sends a letter about Suzu to her oldest sister Sachi. After reading the letter, Sachi attends the funeral. Soon, Sachi invites Suzu to live with and Suzu accepts. The four sisters begin to live together.