Sore o Ai to Machigaerukara

Ito Kaya is a full-time housewife and has been happily married to her husband Tadashi for 15 years. However, they have not had sex for a long time. One morning, Kaya asks if he has a lover, and learns that he knows that she has a lover too. In fact, Kaya has been having an affair with manga artist Seiichiro. Meanwhile, she finds out that the chiropractor at chiropractic clinic that she goes to, is her husband’s lover. Through an unexpected turn of events, they all end up becoming acquainted. What will happen to this four-sided relationship between the troubled couple and their lovers?