Female / 28 years old 1st-year OB/GYN resident. She is full of confidence and loves dressing up and going on blind dates. She is obsessed with horoscopes and checks hers every single day. As time passes, she gets used to the work and mainly teaches intern Tak Gi-on. In the beginning, she does a lot of dressings and makes many mistakes, but later on, she gains Gong Gi-seon's support, becomes proficient at her job, and develops a sense of camaraderie with her peers.

Male / 28 years old 1st-year OB/GYN resident. He has a bright and positive personality. He is the mood maker who livens up the ward atmosphere. He is very playful. He sincerely cares for his patients and colleagues. He never loses his smile even in tough situations. He is a former idol from a group called 'High Boys.' In the beginning, he calls 2nd-year Cha Da-hye every day, but he gradually learns the ropes and works with total sincerity even while asking questions.

Female / 28 years old 1st-year OB/GYN resident. She is academically brilliant and values principles above all else. She prioritizes logic and evidence over emotions. She acts calmly and is poor at expressing herself, but has a strong sense of responsibility. Both of her parents and her older brother are doctors. Initially, she is realistic, strives to be number one, and treats patients systematically, but over time, she develops camaraderie, tries to understand patients' emotions, and even starts to smile.

Male / 31 years old 4th-year OB/GYN resident. He is a role model for his juniors. He is kind, deeply considerate, and stays calm in any situation while meticulously teaching his juniors. He is a reliable senior who takes responsibility for difficult tasks. He is a bit of a 'pushover Do-won' who apologizes on behalf of the 1st, 2nd, and 3rd-years when they mess up and handles everything. He is related to Oh Yi-young by marriage.

Male Chief of Gynecology. He has a fiery temper and shouts incredibly loud if a surgery is delayed. To patients, he couldn't be a kinder professor, but to residents, he possesses a temper like fire and a personality like a dog.

Female Chief of Obstetrics. Her nickname is 'The Wicked Witch.' She is the type to tear someone down verbally, then keep picking at the same spot over and over. She has targeted Oh Yi-young, making her a permanent fixture in her surgeries, but she secretly cherishes her. Geum Sae-byeok is her junior.

Male Gynecology professor. He has a bright, cheerful, and kind personality. Rather than just scolding juniors for mistakes, he gives advice so they can grow. He makes the ward atmosphere comfortable and laughs off some of the kids' mistakes. He loves doing rounds, so he often goes on rounds by himself.

Female Obstetrics professor. As time goes on, she starts to see Pyo Nam-gyeong in a positive light. She is Myeong Eun-won's secret backer. She is sensitive, and her nicknames are 'Kkong' and 'Devil.' Like Seo Jeong-min, she subtly grinds the residents down. She especially picks on the robot-like Kim Sa-bi.

Female / 28 1st-year OB/GYN resident. She is blunt and constantly says 'Ah.' She wants to quit her job and has 50 million won in debt from a negative bank account. She is related to Gu Do-won by marriage; her older sister Oh Ju-young is married to Gu Do-won's older brother, so they are in-laws living in the same house. Initially, she seems like the ultimate blunt and lethargic person, but she gradually tries to treat patients with emotion. She caught Seo Jeong-min's eye and is now a permanent assistant in her surgeries. Despite her lethargy, she has emotional moments.

Male / 27 An intern rotating through various departments. In OB/GYN, he often learns from Pyo Nam-gyeong, having previously learned from Oh Yi-young once. He makes frequent mistakes and still has the freshness of an intern. He secretly develops feelings for Pyo Nam-gyeong.