Invite the neighbor to exchange wives for sex

In the 4th year of marriage, Nanami's husband, Koji, had just become independent and was busy with work. Along with the couple, recently the communication between the two also disappeared. Unlike these two, Hibaki, who had moved to another room, lived with her husband, and every time she saw the two of them, Nanami felt jealous. Finally, Hibaki, who knows about Nanami's cold marriage, invites Nanami and Koji to her house and asks them to exchange only for the weekend.