Suffering from a sexless marriage and emotionally overwhelmed, Nao desperately throws herself into housework to suppress her feelings. As she sweats through her chores, her stepson becomes intensely fixated, secretly watching the way her bra becomes translucent with perspiration. Entranced, he begins masturbating—until one day, Nao catches him in the act. By chance, her eyes lock onto his young, erect penis, and she can't look away. Staring at the cock she hasn't seen in years, her heart races uncontrollably, and before she realizes it, she's gripping her stepson's penis tightly. That impulsive moment pulls her into a whirlpool of forbidden emotions.