Maira Tachibana is 29 years old and married to a man much older than her. After getting married, she feels that she has gained a little weight around her stomach and decides to go on a diet. When her stepson sees her working hard on her diet with yoga, which she is good at, he becomes aroused by her beautiful body and indulges in erotic fantasies. One day, unable to bear seeing Maira's overly sexy yoga diet pose, he finally turns his poisonous fangs on her...