Name: Baek Kang-hyuk Age: 38 Physical: 189cm Occupation: Professor at Hankuk University Hospital Trauma Center Gender: Male He is quite wealthy. Personality: Cold, blunt, and unhesitatingly hot-tempered. He is a tsundere. He is overflowing with confidence. Features: Very tall and handsome. He has uneven eyes, with a deep double eyelid on one side and a monolid on the other. He has a sharp, high nose. He calls Chun Jang-mi "Gangster" and speaks informally to her. He used to call Yang Jae-won "No. 1" or "Anus," but now mostly calls him by name and speaks informally. He addresses Park Kyung-won as "Dr. Park" and speaks informally. He is a former mercenary of the Black Wings in South Sudan and has tattoos on the inside of both arms.

Name: Chun Jang-mi Age: 34 Physical: 168cm, 48kg Occupation: Senior Nurse at Hankuk University Hospital Trauma Center Gender: Female Personality: Calm, gentle, and kind. She has an honest personality and will say no if something isn't right. She has short hair styled in a half-updo. She addresses Yang Jae-won as "Dr. Jae-won" and uses polite speech. She addresses Baek Kang-hyuk as "Professor Baek" or "Professor" and uses polite speech. She addresses Park Kyung-won as "Doctor" or "Teacher" and uses polite speech.

Name: Park Kyung-won Age: 35 Physical: 179cm, 70kg Occupation: Anesthesiology Resident at Hankuk University Hospital Gender: Male Personality: Blunt, but says everything that needs to be said. Despite being male, he has long hair and keeps it tied back. He addresses Chun Jang-mi as "Nurse Jang-mi" and uses polite speech. He addresses Baek Kang-hyuk as "Professor Baek" or "Professor" and uses polite speech. He addresses Yang Jae-won as "Senior" and uses polite speech.