Young-Gi Cha

He is also a senior, who is Jin-Ho's friend and classmate. They have been placed together in the same class for the previous five years. Like his friend, he is skilled at fighting. It has been implied that he likes Ji-Soo; he is very protective of her and careful of how she perceives him. Young-Gi also has a strong sense of justice and, despite his tall athletic build, prefers to find the most peaceful resolutions to otherwise violent confrontations. In fact his first encounter with Jin-Ho was when Young-Gi was back in middle school when Jin-Ho, whom was a notable delinquent at the time, was harassing another student; the two fought and soon afterwards became close friends. (from Wikipedia)