Married to a much older man, their relationship had been harmonious—until her husband became infertile and their intimate life came to a halt. One day, he confesses to having a cuckold fetish and asks her to sleep with another man. Confused but willing to fulfill his desire, she begins seducing their neighbor, Kazuki. Though Kazuki struggles to resist her blatant advances, he hesitates to take action. Unable to endure the tension any longer, her husband urges her to go directly to Kazuki's apartment.