Hadesae: The Final Incident 1992 on netflix

A beautiful young girl becomes an eye witness to a cold blooded murder which leads to her brutal rape rendering her insane. Her erratic behavior condemns her to a mental institution, that forces her parents to bribe a janitor at the mental institution and secure their daughter’s escape. Locking her in a secret hide away, they vow to do anything and everything to keep their daughter out of the hands of the authorities. Six teenagers seeking privacy to fulfill their sexual fantasies, accidentally stumble upon the family’s secret hideaway. Gradually and innocently entangling themselves in a web of mysterious events and a world of secrets that wants no part of them.