Confinement Escape: Sex Slave (1997)

One after the other, women who are having lesbian relationships with psychiatrist Yumi are found brutally murdered with their internal organs exposed. Saegusa, a detective and the lover of Miyuki, a female teacher and patient of the doctor, investigates the case. During the investigation, a gang rape case at a school emerges. The victim is Miyuki and the school doctor is Yumi. The culprit has already been found brutally murdered. Meanwhile, Miyuki has been held captive by the perpetrator, with a wire around her neck and forced to masturbate and fondled with oil.