Once Upon a Time in High School, also known as Spirit of Jeet Kune Do: Once Upon a Time in High School, is a South Korean drama film released in 2004. The film is directed by Yoo Ha and stars Kwon Sang-woo and Lee Jung-jin in lead roles. It tells the story of a model student, Hyun-soo, who transfers to Jungmoon High School in the late 1970s. The school is notorious for its strict discipline and the constant power struggles between the various school gangs. Hyun-soo quickly finds himself in trouble with the bullies and becomes a target of their harassment. However, he soon finds a friend in Woo-sik, a fellow student who is passionate about martial arts and has a strong sense of justice. The two boys develop a close bond over their shared love of Bruce Lee movies and begin to train together in martial arts. As tensions rise between the different school gangs and the teachers, Hyun-soo and Woo-sik find themselves caught in the middle of the conflict. The film explores themes of youth rebellion, social hierarchy, friendship, and loyalty. Once Upon a Time in High School received critical acclaim for its realistic portrayal of school violence and its impact on students. The film has been compared to the classic American coming-of-age movie, The Breakfast Club, and is considered a classic of Korean cinema.