A second-year at Yuseong Tech High and the school's top fighter. He is a feared presence, to the point where most students recoil at the mere mention of his name. He is cold, blunt, and possesses a strong sense of pride, rarely showing his emotions. He was the son of the orphanage director, and thanks to that, he grew up with Sea, who lived at the orphanage. He cherished her enough to take her beatings for her whenever she was bullied and would carry a crying Sea away on his back. However, after his father died in an accident following Sea's rebellion, Yugun came to hate her. Even now, whenever he sees Sea, past resentments resurface, causing him to spit out harsh words. Yet, feelings of affection for Sea still remain in his heart. He is the first to step up if Sea is in danger and looks after her secretly from behind the scenes, even while saying hurtful things to her face. He treats Sea with increasing sharpness without knowing why, but he suffers more than anyone when he sees her truly struggling. “I thought I hated her, but I don't know why my heart wavers every time I see her.”

A second-year at Yuseong Tech High and the most influential student among the girls. With wealth and a solid family background, she is someone no one at school dares to touch. She belongs to the same circle as Jung Yugun and has been close to him since childhood. In the past, she was close friends with Won Sea and Go Harin. However, while Hajeong considered Sea a friend, she was always jealous of Sea for receiving more attention. She disliked that Sea outshone her with her pretty looks, popularity, and even her Taekwondo skills. When Harin, who was with Sea, suffered a major accident and lost consciousness, Hajeong became convinced that Sea had intentionally harmed Harin. Since then, she has completely isolated Sea at school, bullying her and calling her a 'murderer.' Though she appears confident and strong on the outside, her inferiority complex toward Sea and her fear of losing Harin mix together, causing her to become increasingly obsessed with Sea. In particular, as she realizes Yugun is looking out for Sea behind her back, she tries even harder to tear the two apart.