Aki and her husband divorced, and her son ended up living with his father. - The day before they left home, Aki was so lonely that she started an affair with her son Naoya. - From then on, Aki's purpose in life was to meet Naoya once a year. - Eventually, Naoya's father remarried, and Aki was worried that her mother-in-law would take Naoya away. - The day has come for Naoya to meet his mother-in-law for the first time...