At first glance, Rumiko and Ikuko, who live together, look like parents and children. While Ikuko is making dinner, Rumiko looks into Ikuko's computer and opens the email that happens to arrive. A picture of a woman of the same age as Rumiko and Ikuko happily holding a birthday cake was attached to it. Rumiko feels complicated. Moreover, Ikuko leaves the room on the phone from the young woman while eating. Rumiko, who is left alone, can't organize her feelings ...