Happy Ghost IV 1990

Directed by Clifton Ko Chi-Sum

A group of college kids discovers the remains of an evil warlord from an old cave and brings it to their dormitory, which ultimately awakens the warlord's ghost. It is seeking to avenge his killer, who has since reincarnated as Mr. Hong's snobby girlfriend Annie. With Hong and Annie endangered, Hong's reincarnated spirit takes over to save him and Annie, and defeat the demon.