Yoshino attends a PTA meeting as an officer for his son's new school term, where he meets Ayano, the mother of a girl named Mari. By chance, both are appointed as officers. Yoshino is instantly drawn to Ayano's friendly and elegant demeanor. However, this is just a facade; Ayano's true nature is that of a sinful woman who loves other people's husbands. One day, while working in the gym storehouse, their conversation turns to romance. Reminiscing about her youth, Ayano makes a lewd proposal: "Why don't you try kissing me here?" When Yoshino tries to avoid her, telling her not to tease him, Ayano cuts him off and forcibly steals his lips. From that day on, until his son's graduation, Yoshino spends a whole year drowning in intense, secret "PTA meetings" with Ayano through all four seasons...
