She's On Duty

Running Time: 111 mins
Release Year: 2005
Director: Park Gwang-choon

Cast: Kim Sun-ah
Gong Yoo
Nam Sang-mi

Synopsis:

Take Stephen Chow's Fight Back to School, re-set it in an all-girl's school in Korea, and add a sexy female protagonist, and you'll have some idea of what writer/director Park Kwang-choon (Madeleine)has in store for you in his entertaining action comedy, She's On Duty! Kim Seon-ah (S Diary, Wet Dreams) plays a female detective who has to go deep undercover as a high schooler in order to thwart a plot by the Japanese Yakuza to traffic teenage girls as sex slaves!

Sources: http://silentregrets.com