Female Teacher Diary 3: Hidden Sex (1997)

When she takes off her teacher clothes, her womanhood breaks... Satoko, a new teacher, is frightened by the hungry gazes of frustrated male students, and is bullied every day by delinquent students such as Hinata Masaaki. Unable to resist, she just lets things happen, and her only emotional solace is through computer communications. As she becomes addicted to lewd sex with the people she is communicating with, a shocking event befalls her...