Hiromi Ichinose divorced her husband several years ago and lives with her son Koji. One day, Koji's homeroom teacher Sahara comes to visit and tells her that with Koji's grades it will be difficult for him to get into a university with an escalator system of admission, but if he starts now he will still be able to get a job. Shocked, Yumi is speechless. But Sahara, being the evil teacher that he is, takes advantage of the mother's feelings for her son and uses the promise of a recommended entrance exam as bait to touch her body. Having not had sex for a while, the mother begins to feel pleasure, saying, "For Koji's sake..."