Working as a site supervisor at a small construction company in the city, "Ryo" married his younger female colleague "Mizuki" a year ago and has since been living a relatively stable life. Though their income is limited, he values his family and cherishes each day. However, Mizuki shows little sexual interest, and due to their lackluster sex life, Ryo begins to feel a sense of loneliness. Around this time, he's contacted online by a man named "Nakata," who invites him to join a "wife-sharing circle." The group consists of participants who present their wives and engage in intimate relations with others in a bizarre, unconventional gathering. One day, Nakata sends a forceful message: "I slept with your wife—now it's your turn to hand over yours!"