Yoshisuke loves his wife, but his lower body no longer responds to sex with her, and Yuji is too casual and indifferent in his caressing of her. The two husbands, who live in the same apartment building, enter into an agreement to sleep with each other's wives in order to stimulate their rutted sex life. The wives are bewildered by their selfish husbands' arrangement, but they gradually become addicted to their lewd and twisted relationship...
