Twenty (2001)

Highschool student Myeong-ju dreams of becoming an actress and begins sleeping with the equally young Seong-ho who wants to be a movie director. Myeong-ju is convinced its love, but Seong-ho is more interested in filming her naked. When Myeong-ju's mother walks in on them having sex, it's the end of Myeong-ju's dreams and the beginning of a harsh reality