Stalking Love ~The Approaching Shadow~(2005)

Maki, is a new teacher at a night school and is adored by her students. Secretely, she is dating one of them, Toru. One day, Osawa, a student in Maki's class stops attending the lectures prompting Maki to visit him at home. However when she arrives, Maki is persuaded into having sex with Osawa. She gives in on the condition that he won't tell anyone, but finds one day a test paper that hints at her relationship with Osawa. From that day on, an ominous shadow begins following Maki...