Hitozuma Swapping Seikatsu

Tatsuya has a wife, Chizuru. They used to love each other, love passionately. But, their love gradually becomes colder and colder.... One day, when he is on his way home, he sees Chizuru walking with a man. He stops them, and asks them what's going on. Another man stops their quarrel, and tells them that he is a boss of a swapping club. He gets interested in it, and visits the club room with Chizuru...