Wet With a Whip (1980)

Koji, a high school boy, falls deeply in love with his female teacher and eventually becomes a stalker. As he spies on her room, he notices that she indulges in masturbation every night, and it becomes a habit for him to sneak out of the house to peek. The female teacher notices this and one day seduces the boy by deliberately showing him how she masturbates, in an attempt to get him excited. Since then, their relationship has developed into one of intense caressing and lewdness, and every night, under the pretense of teaching the boy the A to Z, she tries out all sorts of positions and sexual techniques. The boy's refractory lower body, on the other hand, captivates her...