Airi, who lives modestly with her husband, a doctor, in a housing complex, one day witnesses her husband cheating on her. Beside her husband is a married woman who lives in the same housing complex...yes, her husband is having an affair with another married woman. She consults the other woman's husband, Tanaka, about it, but he doesn't believe her, so they decide to spy on the moment of the affair together. Hurt by having witnessed the decisive moment, the two try to fill the loneliness by getting closer to each other. With their life partners stolen from them, the two begin an affair, seeking each other out with unfulfilled hearts...