The husband's sex drive deteriorates day by day. In contrast, his wife Mirei is bursting with desire. The husband's brother, her brother-in-law, is rough and smells of sweat, which Mirei slightly dislikes. She shows her disgust as he comes in, reeking of sweat. She immediately urges him to take a bath. After bathing, Mirei's mood improves slightly upon seeing her brother-in-law, but she learns a shocking fact. She had never noticed it because she had always found him repulsive, but her brother-in-law's member is much bigger than her husband's. Even if she tries not to notice, she finds herself looking at it. Gradually, Mirei starts having lewd fantasies... Unable to stop thinking about it, Mirei comes up with an idea...
