Onna kyôshi: Seito no me no maede

The lovely Reiko has taken a new teaching job at a creepy old high school. She is an extremely attractive woman and the young students in her class have fallen for her. One night, after tennis practice, she is brutally assaulted in the locker room shower by a man with a stocking over his face. Left on the floor naked and in shock, she discovers a single puzzle piece left behind by the crazed man. (imdb)