Following her film success, Kim began to establish a niche for herself in comedies, often appearing as a straight-talking and not particularly demure comic heroine. She appeared in three films in 2003: a memorable cameo appearance in the period comedy "Once Upon a Time in a Battlefield", opposite Im Chang-jung in the commercially successful "The Greatest Expectation", and together with Cha Tae-hyun in the little-watched "Happy Ero Christmas". In 2004 she took the lead role in "S Diary" as a jilted woman who decides to get revenge on her ex-boyfriends.