The protagonist, Makoto, is an ordinary student with a secret that he cannot reveal to others. He has developed feelings for his best friend's mother, Misaki, and is attracted to her youthful beauty, large breasts, and curvaceous body. Makoto fantasizes about Misaki and masturbates to thoughts of her regularly. One day, while alone with Misaki at his friend's house, Makoto confesses his feelings to her. Misaki, who loves her husband and son deeply, is unexpectedly moved by Makoto's sincerity and agrees to have sex with him, but only once. However, Makoto cannot keep his promise and continues to seek out Misaki's mature body for pleasure. Similarly, Misaki becomes obsessed with the joy of teaching a boy she has treated like her own son about sex, and they both become consumed by their desires.