Every summer, the husband of the main character, Yumiko, goes on a business trip. She feels incredibly lonely and experiences complete sexual dissatisfaction. In her husband’s office, Yumiko discovers a porn magazine, “Koteriya,” and begins to masturbate frantically, imagining her husband fucking her hard. At that very moment, Yumiko's neighbor, Kazuya, appears from nowhere… Yumiko is unable to resist the young male’s sexual desire, and soon she becomes his sex toy.

Yumiko goes to a naughty cosplay event to find out the truth about her husband’s summer business trip. It would seem that she has an ideal disguise, and she will easily expose her husband, but the libertine Kazuya goes on the trip with her…