Two local girls, Matsuda and Tanigawa, moved to Tokyo around the same time. Tanigawa works at a real estate company as a salesman and has a very outgoing personality. Matsuda, on the other hand, works quietly at the city hall and has more of a reserved demeanor. They bumped into each other while working away from home. As they caught up on their recent activities, Matsuda mentioned that things weren't going well between her and her husband lately. Upon hearing this, Tanigawa came up with an idea to host a party at her place where she would invite both couples. Her plan was to encourage them to swap partners and participate in some swinging activities.
