Swapping wives to find strange feelings with the neighbor

In the 4th year of marriage, Nanami's husband, Koji, is both independent and busy with work, in addition to the constant changes, even the recent marital affairs are no longer there. Unlike these two, Hibiki, who moves to the opposite room, has a good relationship with her husband, and Nanami will be jealous of him whenever he sees the couple. Eventually, learning of Nanami's cold marital relationship, Hibiki invites Nanami and Koji to her house and proposes to swap the couple only on weekends.