The story centers around Aoyama Mako, a housewife who is frustrated by her husband Keisuke's erectile dysfunction, leading to a lack of intimacy in their marriage. Keisuke's workplace involves international dealings, and he also acts as a host for foreign exchange students. When the company president's wife falls ill, Mako is tasked with taking care of the exchange student, Billy Wilson.

One day, due to a mishap, Mako and Billy end up in the bath together, and Mako becomes intrigued by Billy's well-endowed genitalia. Despite Billy's promiscuous past, he possesses impressive stamina. As they engage in intimate acts, Mako's pent-up sexual desires from her long period of abstinence lead them to cross boundaries.

Billy helps alleviate Mako's sexual frustration, but his demands become insatiable, and he continues to push her limits, introducing her to new pleasures.

Will she be able to escape from the cycle of pleasure and desire created by Billy?