JUQ-599 Sayuri Hayama is invited by her mother-in-law who wants her son-in-law's big dick all the time.

Sayuri lives in a two-family house with her daughter and her husband. While working as a full-time housewife, she occasionally spent her time working as a swimsuit model through an introduction from an acquaintance. One day, Kunio, her son-in-law, was masturbating in the swimsuit she used. Apparently, his husband's penis is too big and their marriage is not going well. However, Sayuri was captivated by his huge cock and told him that it was for her daughter.