I just watched
The Ghost Theatre, 삼거리 극장, a 2006 South-Korean movie which was great fun!!! I had a hard time believing the local Love & Anarchy film festival hadn't picked this up already and then I tried to find it on IMBD. And looks like it doesn't exist there at all (I tried various search terms: the move name in English or in Korean, or various actors. And nada. Nothing. It's a ghost (bad joke) :P.
First of all, it's Korean musical that is set in a movie theatre. And it has ghosts, movie meta, monsters and a happy ending for the metaphysical love story. Plus some damn catchy songs :D:
Click to view
I can't get this song out of my head :D...
A young girl is looking for her grandmother who has gone missing telling she wants to see the movie she once appeared in. The girl ends up in a dilapidated movie theatre which doesn't have much of an audience. But she finds out there is a group of ghosts inhabiting the theatre and somehow their story is related to the movie her grandma appeared in.