JUR-678 | "Yu-kun's dad, let's do something naughty behind your wife's back?" Ayano, who disrupts the morals of the PTA, and her monthly lewd, unprotected sex meetings. Kato Ayano

As his son starts a new school term, Yoshino is asked to attend a PTA meeting as a PTA officer. There, he meets Mari-chan's mother, Ayano. By chance, both of them are appointed to the PTA. Yoshino is instantly drawn to the friendly and elegant Ayano. 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 storage room, the conversation turns to romance. Reminiscing about her youth, Ayano makes a lewd suggestion to Yoshino: "Why don't we kiss here?" Yoshino tries to avoid her, telling her not to tease him, but Ayano interrupts him and forcefully steals a kiss from his lips. And from that day on, throughout the four seasons (one year) until his son graduates, he becomes immersed in intense PTA meetings with Ayano...