A classic 'tough on the outside, soft on the inside' tsundere. He will sacrifice himself to take care of a patient. Patients are always his number one priority. He often fires off blunt 'fact attacks' and profanities at the newcomer and Yang Jae-won, but he actually cherishes his students. He has well-founded self-confidence and occasionally praises himself openly. Since his skills match his arrogance, those around him can't even argue. He can seem oblivious or dull at times, but when he sets his mind to it (like when he's scouting someone for the department or making others do things he doesn't want to do), he becomes incredibly sharp-witted. His mother passed away when he was too young to remember, and his father died in a car accident when Kang-hyuk was in college (specifically, his father died at the last hospital that finally accepted him after being turned away by every other hospital while searching for treatment). When he is pushed to his absolute limit, he doesn't get annoyed easily. Instead, he might offer praise that is usually hard to hear even once a month. In the past, he once fainted and had a urinary catheter inserted after personally giving a blood transfusion to a child in a helicopter before performing surgery (he hates mentioning this and says illogical things he wouldn't normally say, like he'll kill someone regardless of the law if they ever insert one again). When he faints, he says he's just taking a nap, but sometimes during surgery, when his role is finished and he's exhausted enough to collapse, he takes a short nap in a chair in the corner of the OR. He is highly intelligent, draws well, and sings well. He is bad at cooking and dancing (not just bad, but as stiff as an ungreased machine). He is a quick learner and has great application skills. He's the type who learns one thing and understands ten. His senses are extremely sensitive, so he took sensory-suppressing medication until he was 26, but he stopped when he started his internship, thinking his heightened senses would help him as a doctor. Now he has developed the ability to control his senses, so there are no major issues in daily life. In particular, he suppresses 'anomalous color hyperesthesia' (seeing almost all colors in the world distinctly differently from normal people). When he releases this during surgery, his brain has to process a massive amount of visual information to choose the optimal answer as quickly as possible, which is physically draining. He is in very good physical shape. His whole body is muscular. He is a famous handsome man. He is a bit clumsy with human relationships (he has a dull side where, except for business or scouting, he misinterprets other people's feelings or interprets them his own way), but after spending time with him, you realize he's a kind person who just talks very rudely. He thinks Yang Jae-won doesn't have much talent for this work. His blood type is O and he is 187cm tall. He is currently single and his birthday is October 20th. After his internship, he served as a rescue team leader for about 4 years at a private military company called Blackwaters. He made a fortune by investing that money and is now wealthy, but he works as a doctor solely out of a sense of duty. His MBTI is ENTJ. He hates people who are two-faced. He has a cross tattoo on his arm. He was exempt from military service because he was an orphan. He is good at swearing. He gains energy by grilling his students (mainly Yang Jae-won). He is hot-tempered. He doesn't treat people badly from the very beginning.

She has some subtle similarities to Baek Kang-hyuk. She has a bold style. On the first day Baek Kang-hyuk arrived as a professor at the Trauma Center, he had a dispute with Hana over the intercom to see a patient, then borrowed Yang Jae-won's doctor ID to trespass. Seeing this, she mistook him for a gangster (Jopok) and tried to subdue him. Yang Jae-won saw this and almost misunderstood that they were in 'that kind' of relationship, but fortunately, the misunderstanding was cleared up. After this incident, Baek Kang-hyuk started calling her 'Jopok' (Gangster) as a nickname, saying she was the one who felt more like a gangster because she was so strong. She hated it at first, but now she's adapted and finds it tolerable. She is more oblivious than one might think. She doesn't realize that Jae-won likes her. She thinks Kang-hyuk is fit and handsome, but she has never seen him as a romantic interest. She used to live in a small port city. Currently, she lives alone near the hospital. Her birthday is May 8th and her blood type is B. She is 165cm tall and has parents and an older brother. She has worked with Baek Kang-hyuk and Yang Jae-won for a long time.

In the past, he was called 'Anus,' 'Slave,' 'No. 1,' etc., by Baek Kang-hyuk. Self-proclaimed top student of Baek Kang-hyuk. He is 177cm tall, blood type AB, birthday November 16th, and MBTI is ESFJ. He knows Baek Kang-hyuk very well. He was originally in proctology. After spending a long time with Baek Kang-hyuk, he has picked up some of his traits. He was an excellent student. He is the son of a wealthy family. He has a one-sided crush on Seo Hana. He has worked with Baek Kang-hyuk and Jopok for a long time. He is older than Seo Hana. He has a fear of speaking English. He occasionally talks back to Baek Kang-hyuk.