Mayumi Kawamura is 43 years old. She is a housewife from Ibaraki who usually works as an office worker at a publishing company. Due to her job, Mayumi often comes across a variety of magazines and books. Recently, she has been interested in the sex features and erotic ads for dating sites that she often sees mixed in with her favorite entertainment articles. She couldn't help but compare the nighttime activities with her husband, which have decreased significantly recently, to the catchphrases about infidelity and cheating that are written as if they were true... and so she inadvertently applied. What does cheating really taste like? Today, she will finally experience it for the first time!