Ryo is a site supervisor at a small construction company in Tokyo. A year ago, he married Mizuki, a younger woman who works at the same company. Although they are by no means wealthy, they live a happy life without any inconveniences. However, Mizuki doesn't like sex very much, and perhaps because they don't have a nightlife, Ryo is invited by a man named Nakata, whom he met on an online site, to join a meeting of a "wife-offering circle." It is a very perverted circle where members offer their wives to each other. One day, Nakata approaches Ryo. "Since you did it with my wife, you should offer yours to me too!" he says.