Kannō kyōshitsu: ai no tekunikku (1972)

Tormented by his first sexual stirrings, the teenager Isao dreams every night of his gym teacher Ikuko. He finally opens her heart but she rejects his advances. Frustrated, Isao invents all sorts of stratagies to disgust Ikuko´s fiance, a professor of chemistry in the same school. As his plan fails, he plans a radical solution...and the results turns out to be...