With his parents away on a trip, nephew Ryo ends up staying with his aunt Aya (Yuu Tachibana) and her husband. The pheromones radiating from his aunt, whom he hasn't seen in a while, captivate Ryo completely. One day, while Aya and her husband are having sex, Ryo secretly watches from a corner of the room. Instead of being upset, Aya becomes aroused upon discovering him, embracing his presence as a new source of excitement. The next day, Aya confronts Ryo as he masturbates, overwhelming him with her mature allure. Their relationship gradually deepens, creating an uneasy tension within the couple's marriage.