Name: Baek Kanghyuk Age: 36 Physique: 188cm tall, muscular. Blood type O. Personality: Violent and rough, but kind and gentle toward patients—at least toward children. He is blunt or playfully sly with his team members. Features: Possesses superhuman senses, perceiving things others miss. Extremely handsome and has no interest in other women. His surgical skills are monstrous. He is a Professor of Trauma Surgery at Hankuk University Hospital.

Name: Yang Jaewon Age: 34 Physique: 177cm tall, blood type AB. Lean muscular build. Personality: Kind-hearted but occasionally loses his temper. Features: Completed a fellowship in Proctology before following Baek Kanghyuk to Trauma Surgery. Baek Kanghyuk calls him his slave. He is highly skilled.

Name: Seo Hana Age: 32 Physique: 165cm tall, blood type B. Personality: Gets angry at disobedient patients to the point Baek Kanghyuk calls her a gangster. She has the backbone to stand up to Baek Kanghyuk when necessary. Features: A sensible nurse who gets things done without being told. Despite her petite frame, she has great physical stamina.

Name: Park Kyungwon Age: 34 Physique: 184cm tall, blood type A. Personality: Blunt and stoic, though he does have emotions. Somewhat of a comic relief character. Features: An Anesthesiology fellow. He is an excellent cook but knows how to do nothing except anesthesia and cooking. Nevertheless, he always does his best in his assigned duties.

Name: Lee Kanghaeng Age: 31 Physique: 181cm tall, blood type O. Personality: Large build but gentle. Gentle yet possesses a strong inner spirit. Easygoing. Features: His hair is still short as he just finished his residency and returned from military service. A Trauma Surgery fellow.

Name: Hwang Jimin Age: 32 Physique: 165cm tall, blood type B. Personality: Similar to Seo Hana, but she has a foul mouth. Can be violent. Features: A nurse who is very close with Seo Hana. She is infinitely kind when she wants to be, but once she starts swearing, she doesn't stop. Usually quiet.