A voyeuristic-style documentary depicting the first swapping experience between the Maruyama and Sugahara couples, living together under one roof in an intense cohabitation setup. Maruyama Kenji and Reiko participate in an attempt to break the monotony of their marriage. Reiko initially joins solely for her husband's sake, but quickly becomes captivated by the allure of another man. Meanwhile, the highly sexual Sugahara Hiroshi and Natsumi eagerly indulge in passionate encounters under the premise of their first swap. Over the course of a two-night, three-day swapping experience, the situation escalates into an extremely intense four-way orgy. The film captures the awakening of new desires and the heated relationships that emerge as both couples discover unexpected attractions in each other.