The Hatanos moved in downstairs, so they visited the Otsukis, who lived upstairs, to say hello. The moment they met, Mr. and Mrs. Otsuki felt the desires they had hidden in their bodies suddenly float to the surface. While Yui is away, Mrs. Otsuki goes downstairs and successfully fucks her husband. Hibiki enjoyed making love to Yui's husband as well as her own. One day, the Otsukis invited the Hatanos to dinner, and there, Hibiki talked about her relationship with Yui's husband. When she learned the truth, Yui began an illicit relationship with Mr. Otsuki. So what will happen to these couples next?