VENU-919 Mizuki Yayoi plays with her dirty father-in-law's wife who has retired and has free time.

After her mother-in-law passed away, Mizuki decided to live with her father-in-law. Unlike her husband, who is a working man, she begins to open up to her father-in-law, who always cares about her, but... Behind his father-in-law's kindness, an ugly desire swirled. He was planning to obtain Mizuki's beautiful and attractive body. Unbeknownst to her, Mizuki, who exposes her defenseless side, is about to be attacked by her father-in-law's poisonous fangs.