The Hatano couple had a problem. Akira was unable to get an erection during sex, and they had not had sex for over a year... To be honest, Yui was also suffering from a burning desire to have sex. The Kuroki couple, who lived next door to her in the same apartment, were a very free-spirited couple about sex, and were not afraid of being seen by others. One day, when Yui was passing by in the shared hallway, she witnessed the Kuroki couple having sex through the gap in the door...
