The Chinese philosopher Chuang-Tzu dreamed he was a butterfly and when he woke up he thought maybe he now was a man in a butterfly's dream. I think you can see the whole film as a dream and as such it is just perfect. In the real world it's of course impossible for a Japanese to be understood in Corea, speaking his own tongue -it's not like e.g. a Swedish actor in a Norwegian or Danish film- but in a dream it's even natural. Also, the "comical", bloody stay-awake-scenes should be seen as dream-scenes; I guess in real life you would drink a lot of coffee instead of stabbing yourself! So, my recommendation is: give the film a second chance and look upon it as a dream.