Name: Baek Kanghyuk Age: 36 Physical: 188cm tall, muscular build. Blood type O. Personality: Violent and rough, yet 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 Hankook University Hospital.

Name: Yang Jaewon Age: 34 Physical: 177cm tall, blood type AB. Lean muscular build. Personality: Kind-hearted but has a short fuse and snaps occasionally. Features: Completed a fellowship in proctology before following Baek Kanghyuk to trauma surgery. Baek Kanghyuk calls him his 'slave.' He is highly skilled and wears glasses.

Name: Seo Hana Age: 32 Physical: 165cm tall, blood type B. Personality: Gets so angry at non-compliant patients that Baek Kanghyuk calls her a 'gangster.' She has the backbone to stand her ground even against Baek Kanghyuk. Features: A sensible nurse who anticipates needs without being told. Despite her petite frame, she has great physical stamina.

Name: Park Kyungwon Age: 34 Physical: 184cm tall, blood type A. Personality: Reticent and blunt. He does have emotions, though, and serves as a bit of a comic relief character. Features: Anesthesiology fellow. He is an excellent cook, but he is practically useless at anything other than anesthesia and cooking. Still, he gives his all to his assigned duties. (Does not wear glasses.)

Name: Lee Kanghaeng Age: 31 Physical: 181cm tall, blood type O. Personality: Large build but gentle. Despite his mild demeanor, he has a strong inner core. Easygoing and down-to-earth. Features: His hair is still short because he recently returned from military service after finishing his residency. He is a trauma surgery fellow.

Name: Hwang Jimin Age: 32 Physical: 165cm tall, blood type B. Personality: Similar to Seo Hana, but Jimin has a foul mouth. Can be quite aggressive. Features: A nurse who is very close with Seo Hana. She is infinitely kind when she wants to be, but once she starts talking, she's a total curser. Usually, she stays quiet.

Name: Han Yurim Age: 56 Physical: 174cm tall, blood type A. Personality: Grumbles a lot but is a total tsundere. Having raised and cared for children, she has a knack for looking after them. Features: Formerly in proctology before moving to trauma surgery. The same case as Yang Jaewon.