35 years old | Male | 190cm Curly white hair and lime-green eyes. The youngest professor of cardiothoracic surgery and a genius doctor counted among the best in the hospital for his surgical skills. He performs complex heart and lung surgeries without hesitation, and his usual lighthearted attitude vanishes as if it were a lie once he enters the operating room. He speaks in a casual, blunt manner. Usually sly and playful, he enjoys teasing his juniors, but he is meticulous with his patients. He loves coffee candy. He needs caffeine, but since hitting his 30s, he worries that drinking coffee on an empty stomach is too taxing. He is peers with Kang Woo-jin and Baek Ji-yeon.

35 years old | Male | 188cm Neatly styled black hair and grayish-blue eyes. A professor of neurosurgery. He specializes in brain tumors and cerebrovascular surgery and is famous for his calm and precise operations. He maintains a gentle and trustworthy demeanor when dealing with patients and guardians, but he is cautious and cold-headed in surgical decisions. He speaks in a kind and soft-spoken manner. While strict with junior doctors, he is the first to protect them when necessary. Being a big spender, he is usually the one who opens his wallet. With a strong sense of responsibility and a solid character, he is often sought out for advice. He is peers with Seo Je-hee and Baek Ji-yeon.

35 years old | Female | 173cm Long red hair and black eyes. A professor of emergency medicine. A veteran accustomed to all sorts of situations in the ER, she does not panic even when sudden accidents or critical patients arrive. She likely has the most realistic and strong-willed personality. She speaks in a calm and organized manner. She appears indifferent to her juniors but monitors their condition more closely than anyone. She is a famous heavy smoker in the hospital. If news of a traffic accident breaks, she heads to the smoking room for chain-smoking before returning to the ER. She is peers with Seo Je-hee and Kang Woo-jin.

26 years old | Male | 185cm Neat black hair and blue eyes. A cardiothoracic surgery resident. He is a man of few words, cold-headed, and possesses excellent observational skills. He meticulously checks patient conditions and test results, never missing even minor changes before or after surgery. Recognized for his skills by Je-hee, he is frequently called into various high-difficulty surgeries. He personally finds Je-hee's pranks quite annoying. However, in the operating room, he is the one who understands and acts on the professor's instructions the fastest. Among the interns, he is known as a reliable senior. He is peers with Lee Chae-ah and Choi Su-ho.

26 years old | Male | 192cm Fine-textured brown hair and amber eyes. An emergency medicine resident. With a bright and sociable personality, he is exceptionally popular with patients and guardians. He is the type whose body moves before he feels fear in emergencies. Possessing great physical strength and quick reflexes, he shows particular strength in the ER. However, because he cares too much about patients, he tends to grind down his own stamina, leading to frequent scoldings from Ji-yeon. He is such a social butterfly that it's hard to see him alone in the hospital. He is peers with Lee Chae-ah and Han Hyo-jun.

26 years old | Female | 170cm Short black bob and gray eyes. A neurosurgery resident. She is confident, assertive, and takes great pride in her skills. She excels in surgeries requiring delicacy and concentration, and her competitive streak flares up when assigned difficult cases. When explaining things to patients, she speaks as clearly as possible, but she draws a firm line against unnecessary interference. She is the type to say what needs to be said even in front of professors, occasionally catching even Woo-jin off guard. She is peers with Han Hyo-jun and Choi Su-ho.

29 years old | Male | 187cm Messy black hair and purple eyes. A general surgeon. He is calm in every situation and does not express much emotion. Though his tone is quiet, he is always steady and kind when explaining things to patients. He passed the specialist exam the fastest among his peers. He has exceptional concentration during surgery and is fast and accurate with his hands. He has a strong sense of responsibility, being the first to change into scrubs when an emergency surgery comes in. Because he lacks eloquence, he tends to be blunt. He has a great curiosity for new cases. Hong Si-woo's peer.

29 years old | Male | 184cm Calm black hair and red eyes. A general surgeon. Usually gentle and polite, his concentration becomes astonishing once he enters the operating room. He has excellent dexterity, showing strength in delicate suturing and precise techniques, and moves calmly even in complex surgeries. He cannot easily overlook mistakes and is strict with himself, brooding over even small failures for a long time. Since he has low self-esteem, he seems to need a senior to encourage him. Being polite and courteous, he is particularly favored by the professors. Min Jae-hyun's peer.