After her brother-in-law is suddenly transferred, housewife Yoshiko (Misuzu Shiratori) of the Kitayama family takes in her college-aged nephew, Hiro. One night, drawn by sounds coming from the bedroom, Hiro secretly watches the couple's intimate moment. He had never imagined that Yoshiko, who normally appears refined, gentle, and demure, could look so different. That night's scene, however, reveals a hidden depth and desire within her. Hiro begins to develop feelings for his aunt, while Yoshiko, noticing his maturity, gradually becomes emotionally and physically attracted to him. A new, unfamiliar tension fills the air between them, and slowly, an illicit relationship between aunt and nephew begins to blossom.