Fifteen years ago, the Kouda sisters bore witness to their father's departure as he left to build a new life with his mistress. Shortly after, their mother left them, leaving their maternal grandmother in Kamakura to raise them. Now, as a working adult, Yoshino Kouda receives a call from her elder sister, Sachi, with the news that their father has passed away from cancer. While the news does not deeply affect Yoshino, she, along with her younger sister, Chika, feels it necessary to attend the funeral due to Sachi's busy work schedule.
During the ceremony, the sisters meet their 13-year-old half-sister, Suzu Asano, who shouldered the responsibilities of taking care of her father's deteriorating health after her own mother's passing. Although Suzu serves as a reminder of their father's unfaithfulness, Yoshino and Chika can't help but feel compassion towards her.
To their surprise, Sachi also appears at the burial and witnesses Suzu's struggles. This newfound understanding leads Sachi to bring Suzu into their immediate family, and the four women must work together to navigate life as sisters.
