Okay, first things first: No bikini's in this film. The title pretty much makes no sense, so don't choose this movie based on the title.
The movie opens with a preview of the final scene, which I point out because you may get lost pretty quickly if you don't speak Korean... which I don't (the English subtitles were not written by anyone fully fluent in English.) Our hero... literally... is a geeky young socially awkward everyman that witnesses a cute girl being accosted by a group of thugs. He comes to her defense, beats up her marauders, and they run away together to his tiny apartment where he eventually learns there's something very strange about the girl he believes he "rescued"...
...or did he?
No nudity, but definite sexual situations to rate this an R. Done in art-house style, but with a script right out of college film class.
Interesting movie. Dumb, but interesting.
