Oh Lee Young 1st-year OB/GYN resident. Female, 28 years old. A second-time resident applicant. This is because she quit her previous job after biting the hand of a dermatologist who was sexually harassing Chae-ryeong. She became a resident to pay off her debts. She is Do-won's in-law and has a crush on him. She is on the blunt side but has a lot of affection and is the kindest. Sometimes she is too honest.

Eom Jae-il 1st-year OB/GYN resident. Male, 28 years old. Former member of the idol group High Boys. He works the hardest among the first-years and asks the upper-years many questions. He respects Eun-mi and tries to become a senior like her. He carries a lot of things in his bag.

Pyo Nam-kyung 1st-year OB/GYN resident. Female, 28 years old. Daughter of a mandu shop owner. She empathizes the best and cries easily. She wears full makeup every day. High school classmate of Lee Young. Self-proclaimed fashionista who loves dressing up. She is gradually finding her work as a doctor rewarding. Among the first-year residents, she is the most skilled except for suturing.

Kim Sabi 1st-year OB/GYN resident. Female, 28 years old. Perpetual top student. Her medical knowledge is the best among the first-years. Her empathy skills are a bit lacking, but her will to learn is clear. She respects Professor Seo Jung-min. She was a fan of High Boys. Both of her parents are doctors.

Gu Do-won 4th-year OB/GYN resident. Male, 33 years old. OB/GYN ace. A fixture at the hospital. He takes good care of his juniors and is kind. He is Lee Young's in-law. He hates establishing strict discipline or hazing. However, he scolds sharply when he needs to. He arrives at work the earliest.

Seo Jung-min Obstetrics Professor. Female. Has a daughter in 8th grade and a 9-year-old son. The power player of Yulje Hospital's OB/GYN department. A young professor with a lot of experience in deliveries and surgeries. Colleague of Ryu Jae-hwi and Gong Ki-sun. She nags a lot but cherishes Oh Lee Young the most among the first-years. She has nicknames like 'Wicked Witch' and 'Question Mark Killer'. She doesn't particularly like Myung Eun-won. She has a routine of saying "Hello!" to the babies she personally delivers or operates on.

Gong Ki-sun Obstetrics Professor. Female. Has the nickname 'Amadeus the Devil'. Her personality changes depending on her mood that day. She bickers with Jung-min but is a colleague who comes running when needed. She trusts Jung-min deeply. She cherishes Nam-kyung the most among the first-years.

Ki Eun-mi 3rd-year OB/GYN resident. Female, 30 years old. The kindest among all medical staff at Yulje Hospital and takes great care of her juniors. She especially makes sure they eat well. She comforts them, saying it's okay even if they make a mistake. She is so kind she has the nickname 'Eun-mi Teresa'. She is on the cute side and is evaluated as a hybrid of a human and an angel.

Cha Da-hye 2nd-year OB/GYN resident. Female, 27 years old. A 'young old-timer' (kkondae). She uses polite speech even to the first-years. She occasionally points things out so that her juniors don't go astray. She has the best relationship with Jae-il among the first-years. She is the discipline leader, but she isn't a closed-minded character, as she genuinely rejoices when something good happens to a junior.

Geum Saebyeok 1st-year Obstetrics Professor. Female. A junior professor whom Jung-min cherishes very much. A workaholic who works at the hospital even though she is full-term pregnant. Because of this, she is often scolded by Jung-min. She puts effort into nurturing juniors, such as letting Lee Young perform ultrasounds. She is confident that she can give birth well. She is quite skilled.