Question: Yoo Ha, is a South Korean film director, screenwriter and a contemporary poet, he directed the critically acclaimed film,  "Once Upon a Time in High School" (2004), is a South Korean drama film, the background of the film is set in a high school in which country?
Sentence (from "Once Upon a Time in High School"): The background of the film is set in a high school in South Korea, .
Relevant evidence: Yes