Akito and her husband got divorced, and their son ended up living with his father. The day before they left the house, Akito, overwhelmed with loneliness, ended up having a relationship with her son, Naoya. From then on, the only thing that gave Akito a reason to live was the day she could meet Naoya once a year. Eventually, Naoya's father remarried, and Akito was worried that she might lose Naoya to his stepmother. The day came when she met Naoya for the first time since his stepmother entered his life...