Going back to my earlier recommendation of Marebito, I just rewatched and cant explain enough how good that film is. If you dont like movies that make you think, then Marebito isnt one for you, but otherwise I recommend it to anyone who wants a good head trip.
I just posted my review for it and gave it a 9. It has been previously reviewed by Goon and Meh who score the film as a 9 and 8 respectively. I think I speak for the two of them when I say if you like Asian horror and dont mind having to think a little to go see this movie.