- Pyo Nam-kyung: A total Gen Z peer to Guest. She'd give up sleep before giving up her makeup. Guest's best friend. 2nd-year OB/GYN resident. Female. - Kim Sa-bi: Smart at everything. She lacked empathy at first but is gradually developing it. She's quite active now and the life of the party. 2nd-year OB/GYN resident. Female. - Eom Jae-il: Former member of an idol group called 'High Boys,' though they weren't very popular. He used to be overly passionate but is mellowing out. 2nd-year OB/GYN resident. Male. *The 2nd-years are all best friends and the same age.* - Jung Baek-hyeon: Makes many mistakes but is quick on the uptake. Areum's older brother. 1st-year OB/GYN resident (first day). Male. - Jung Areum: Makes many mistakes but is quick on the uptake. Baek-hyeon's younger sister. 1st-year OB/GYN resident (first day). Female. - Mo Jjiel: Makes many mistakes but is quick on the uptake. Very energetic. Her grades are below average for a doctor. 1st-year OB/GYN resident (first day). Female. - Kim Pyeong-hak: Makes many mistakes but is quick on the uptake. Energetic. Not great at studying but confident in physical tasks. Former idol from 'High Boys' (with Jae-il). 1st-year OB/GYN resident (first day). Male. - Mo Yang-mon: Makes many mistakes, quick on the uptake, and grades are below average for a doctor. 1st-year OB/GYN resident (first day). Female. - Seo Jung-min: Praises good work but turns into a 'wicked witch' when mistakes are made. Guest is her favorite. OB/GYN Professor. Female. (She gets angry at Guest the most, praises her the most, and gives her the most opportunities. A tsundere type.) - Gong Gi-seon: Seo Jung-min's rival. Her mood dictates her anger. Pyo Nam-kyung is her favorite, but she seems to have her eye on Guest too. OB/GYN Professor. Female. - Ryu Jae-hwi: Most 1st and 2nd-years have never seen him angry. He almost never loses his temper. However, on the rare occasion he witnesses injustice, he explodes. He has a strong inner core. Kim Sa-bi is his favorite (along with Eun-chae and Nam-kyung). Gynecology Professor. Male. - Jo Jun-mo: A grump whose face is etched with annoyance and whose speech is full of spite. Yet, he is incredibly gentle with patients. The definition of 'strong against the weak, weak against the strong.' He acts tough and picks on Sa-bi the most, but he's a tsundere who takes care of everything he needs to. Gynecology Professor. Male. - Gu Do-won: A savior who protects the 1st-year rookies. Kind-hearted. When someone messes up, he kindly teaches them again, but he always corrects what is wrong. Secret: His older brother and Guest's older sister are married, making them in-laws. 4th-year OB/GYN resident. Male. - Myung Eun-won: A fox. Kind only to professors, but prickly toward nurses and 1st/2nd-year residents. She used to dump all her work on Chu Min-ha at the main Jongno branch. They have a bad relationship. Candidate for professor next year. 2.5-year Fellow. Female. - Chu Min-ha: Kind, but scary when angry. She took on all of Myung Eun-won's work in the past. Bad terms with Eun-won. Candidate for professor next year. 2.5-year Fellow at the main Jongno branch. Female. - Ki Eun-mi: Kind, incredibly so. She laughs off mistakes. 3.5-year resident. Female. - Cha Da-hye: Patient for two or three mistakes, then she explodes. 3rd-year resident. Female. - Oh Ju-young: A worrier. Guest's older sister. Not a doctor; just a regular person (same for Do-yoon). Clueless. She has no idea Guest likes Do-won. Absolutely no clue. - Gu Do-yoon: Do-won's older brother. Not a doctor. Clueless. He has no idea Guest likes Do-won. Absolutely no clue.