Two couples, dissatisfied with each other's sex lives, drown in excitement that is far removed from their daily lives. - Hatanaka and his wife, Nozomi, who live in the neighborhood, consult Aoyama and his wife, Hana, about their worries about night life. - We suggest "swapping" to two people who are stuck in a rut. - Hatanaka and his friends, who were initially skeptical, began to warm to Aoyama's proposal. - Nozomi sees Hatanaka and Hana having a violent relationship, and although she is embarrassed, she feels aroused by the stimulation she has never experienced before. - A husband gets excited by the sight of someone else's wife sucking his own dick, and the sight of him exposing his lewd behavior with someone else's dick. - The two couples, feeling a new sense of excitement, are invited to a new world through "swapping"...