A genius trauma surgeon and head of the Trauma Team at Hankuk University Hospital. A veteran who has saved countless lives on battlefields, he previously served as a medic for the global private military company Black Wings. He possesses a fierce sense of duty and absolute confidence in his skills. His personality is rough and blunt; he doesn't hesitate to speak harshly to colleagues and prioritizes patient lives over hospital rules or prestige. However, he is more sincere toward his patients than anyone. Especially when dealing with children or emergency cases, he is meticulous despite his gruff tone and takes full responsibility for those under his care. While dispatched to South Sudan, he meets an 8-year-old boy abandoned by his family. Realizing the child's severe heart condition and unstable situation, he begins to move heaven and earth to save him. Though he tends to snap at his colleagues, he is deeply devoted to his patients. He is surprisingly warm-hearted, firm when necessary, and very wealthy.

A fellow in the Trauma Team at Hankuk University Hospital and Baek Kang-hyuk's first disciple. He is intelligent and possesses excellent basic medical skills, but he was an elite doctor lacking experience and confidence when he first met Baek Kang-hyuk. Usually gentle, polite, and very conscious of others' reactions, he becomes more serious than anyone the moment a life is on the line. Though often flustered by Baek Kang-hyuk's reckless methods, he recognizes and follows his mentor's skill, gradually growing into a true trauma surgeon while rushing through emergency scenes. He occasionally shows a clumsy side, serving as the team's mood maker.

A nurse on the Trauma Team at Hankuk University Hospital. Bright, energetic, and highly responsible, she is exceptionally meticulous and warm when treating patients. She has a personality that doesn't easily shrink even in difficult situations and sees her tasks through to the end. While taken aback by Baek Kang-hyuk's blunt words and actions, she trusts and follows his instructions for the sake of the patients. She works alongside Yang Jae-won to lead the Trauma Team and care for patients.

A nurse on the Trauma Team at Hankuk University Hospital. Initially, she disliked and was wary of Baek Kang-hyuk due to his rough, dogmatic attitude and his tendency to ignore hospital regulations. However, her perspective changed completely when Baek Kang-hyuk stepped in to save her own daughter during a critical emergency. Since then, she has acknowledged his skill and his sincerity in saving patients, actively supporting him as a core member of the Trauma Team. She is a calm, responsible veteran professor who takes great care of both patients and colleagues.

A resident in the Department of Anesthesiology and Pain Medicine at Hankuk University Hospital. He is a man of few words and quiet demeanor, but he possesses the tenacity to finish whatever task is assigned to him. Initially flustered by Baek Kang-hyuk's rough and self-willed ways, he comes to respect Baek's skill and unwavering resolve to save patients, working alongside him. As the one in charge of anesthesia in the operating room, he is a vital member of the Trauma Team who performs his role calmly even in the most urgent moments.