Peeping at the female teacher: Privacy exposed (2000)

Kotaro, a high school student earns money by secretly filming his classmate Keiko engaging in compensated dating, filming under the skirts of his other classmates and passing girls and filming in the changing rooms. One day, Kotaro overhears Maki and her friends plotting to rape Hitomi, a female teacher they admire. He tries to warn Hitomi, following her and finds the teacher indulging in the affair with the vice-principal!