Nuns That Bite (1977)

女獄門帖　引き裂かれた尼僧

aka Onna gokumon-chô: Hikisakareta nisô · Torn Priestess

A woman on the run is raped, rescued, then raped again. Escaping, she heads for the hills and finds safe haven at a convent. After becoming a postulant (trainee nun), she catches her fellow sisters engaging in lesbianism, fighting over nothing, hurling snakes at each other, and engaging in mild flesh eating.