The Legend of Seven Cutter

The Legend of Seven Cutter Hangul RRKariseuma Talchoolgi lit. Escaping from Charisma is a 2006 South Korean film starring Ahn Jaemo and Yoon Eunhye.

When a high schooler named Jung Hansoo arrives at Seong Ji High School, he is instantly mistaken for the Seven Cutter. An innocent kid, at first he is blissfully unaware of why the other students are giving him such an icy reception. So when the toughest boy at Seong Ji High School challenges him to a battle for the title of the toughest guy in school, he has no choice but defend himself and fight. Then, when he accidentally wins, things start getting really confusing for him.Soon, Hansoo meets tomboy Han Minjoo, who is not just a great, skilled boxer, but a tough, hardtodealwith knockout as well. After a few coincidences that make him look like a pervert, she also asks him for a battle for revenge. He defends himself by pretending to have a crush on her, even though he likes the pretty, but snotty, girl in school. Minjoo decided to accept his love, and eventually starts to like his unique personality. Later, when Hansoo finally realizes he has fallen for her, Minjoo is heartbroken to find out that he likes the pretty girl, and that he never liked her. Then the bad guys arrive and try to kidnap Minjoo. ........

Source: Wikipedia