In her forties, Rie remains unmarried and lives alone in her childhood home, feeling lonely. During her mother's seventh memorial service, her younger sister Sanae and Sanae's daughter Ruka return to the family home. After a few days, the three begin living together under one roof. One day, while Sanae is out with a friend, Ruka's suppressed feelings spiral out of control. She confesses, "I'm attracted to mature women... women like you, Auntie." Shocked by Ruka's words, Rie struggles to resist her own deep-seated desires, and the two women soon become intimately involved.