Madoka Sakurai and Junko Sakuragi are coworkers at the same company. Perhaps because both their names contain "Sakura," they naturally grew close and quickly became intimate friends. Both are married, but due to the stresses of daily life and strained relationships with their husbands, they've fallen into sexless marriages and harbored mounting sexual frustration. Seeking to satisfy her desires, Junko boldly proposes a plan to Madoka—asking her for "cooperation" in fulfilling their mutual needs.