Evil Sex Maniac(1985)

A perverted nerd uses his computer to determine that his ideal mate would be a teacher. Painting his face kabuki-white to gain confidence, he kidnaps two female high-school students and makes them his rape-torture slaves until they help him nab their teacher. In an abandoned building, the rapes and tortures continue until the teacher finally gets the psychopath's makeup off, rendering him terrified and harmless.