Female Teacher: Cherry Boy Hunt 1976

Hikaru is a female teacher at an all boy's high school. Yata is a mysterious student who transfers from another school. He is the younger brother of a boy who had committed suicide because of his obsession with Hikaru. Yata wants to avenge his brother's death so he recruits two more boys and they rape Hikaru on the school roof. When she discovers the reason for the attack, she stalks them before they can do any more damage.