Till Death Shall We Start.

David died a virgin, and the Doomsday Book says a virgin ghost has no right for reincarnation until he deflowers a human virgin. So David assumes the human shape and goes after Yen. Yen's boyfriend finds out that David is a ghost and warns her, but she doesn't listen. It's now up to him to protect her--against her will--from the sneaky and sex-crazed ghost of David.