Gang Rape (2007)

Original title: 揺れる電車の中で　教育実習生・集団凌辱

Morisaki is passionate about education, and luckily she is hired as an intern in a private secondary school. To her surprise, Morisaki discovers that a group of her students record sex tapes of her neighbour Takara and force her to offer sex. Principal's grandson Fuji is actually the leader of the gang. Morisaki makes up her mind and punishes them strictly. However, those impenitent students even imprison and force her to have sex. Angry Morisaki vows to take revenge..