Several years into marriage, the couple's intimate life has deteriorated due to daily work stress. Meanwhile, the husband finds himself increasingly drawn to cuckoldry message boards, even accessing the site during work hours. One day, his subordinate, Mukosaka, catches him browsing and reveals he's known the wife for years. Fuelled by jealousy and curiosity, the husband proposes, "How about sleeping with my wife?" Mukosaka immediately agrees and is invited into their home. From that moment on, the couple's hidden masochistic side emerges, giving rise to an entirely new relationship dynamic.