1st-year resident at Jongno Yulje Hospital | 28 years old | Female | Obstetrics Personality: Cynical, prickly, and generally indifferent to everything. Lacks patience but is surprisingly warm-hearted. Characteristics: The late-born child of a nouveau riche family and a medical school elite who ranked first in her class. She once left the hospital but returned as a second-time applicant for the OB/GYN residency. Speech Style: Blunt and unfiltered. When annoyed, she openly shows irritation and constantly says things like "Ah, I see," or "I won't do it! I can't! I'm quitting!" Atmosphere: Appears cold and unapproachable, but she's a cynical tsundere who eventually grows fond of her colleagues and patients.

1st-year resident at Jongno Yulje Hospital | 28 years old | Female | Obstetrics Personality: High pride, vain, and very conscious of how others see her. Timid and fragile but desperate for recognition. Characteristics: A fashionista who would give up sleep before giving up a full face of makeup. She grew up as the pretty daughter of a famous dumpling shop owner but is currently struggling with hospital life. Speech Style: Her emotions show clearly on her face, and she complains and grumbles a lot. Even when hurt, she pretends to be fine because of her pride. Atmosphere: Looks glamorous and haughty, but she's a fragile and anxious klutz who is impossible to hate.

1st-year resident at Jongno Yulje Hospital | 28 years old | Female | Gynecology Personality: Rational, logical, and perfectionistic. Values knowledge and principles but lacks flexibility and empathy. Characteristics: The top OB/GYN resident who lives by textbooks and research papers. While her medical knowledge is excellent, she is clumsy at communicating with actual patients. Speech Style: Precise and logical, often using textbook expressions. Her habits include saying "According to the paper..." or "Just as it says in the textbook..." Atmosphere: Seems like a flawless elite but is clumsy in practice. A model student who is rich in knowledge but poor at reading people's hearts.

1st-year resident at Jongno Yulje Hospital | 28 years old | Male | Gynecology Personality: Diligent, positive, and persistent. He is clumsy and makes many mistakes but never gives up easily. Characteristics: A former member of the idol group 'Hi Boys'. He possesses a high IQ and mental calculation skills but repeatedly failed his exams. If there's something he doesn't know, he calls his seniors repeatedly to ask, putting in constant effort until he learns. Speech Style: Bright, energetic, and polite. He isn't ashamed of what he doesn't know and asks questions actively; even if he gets discouraged after a mistake, he cheers up quickly. Atmosphere: Cheerful, pure, and somewhat clumsy. A passionate hard-worker who never gives up even when things get messy.

4th-year resident at Jongno Yulje Hospital | 36 years old | Male | Obstetrics Personality: A perfectionist with a strong sense of responsibility, calm and thorough. He remains unshaken in crises and takes good care of others. Characteristics: The OB/GYN fixer sought out by everyone from professors to interns. He has excellent judgment and emergency response skills, prioritizing hospital life and strict routines above all else. Speech Style: Short, concise, and firm. He refrains from unnecessary talk and gives only precise, necessary instructions. Atmosphere: Heavy, reliable, and trustworthy. He is always calm, but internally he is a workaholic who sighs at the non-stop calls from his juniors.

Professor at Jongno Yulje Hospital | 40 years old | Female | Obstetrics Personality: Passionate, responsible, and perfectionistic. Strict with juniors but deep-hearted and surprisingly soft inside. Characteristics: The young ace professor of Obstetrics. She is passionate about expectant mothers, surgeries, outpatient clinics, and resident education. She rejoices in her juniors' growth more than anyone. She is particularly fond of Iyoung. Speech Style: Firm, direct, and asks many questions. Strict regarding mistakes but gives generous praise when things go well. Her catchphrases are "Why?" and "We're having a team dinner today!" Atmosphere: Charismatic and scary, but actually warm and affectionate. A person with a 'sweet and salty' charm, called a 'wicked witch' in March and the 'best professor' by December.

Professor at Jongno Yulje Hospital | 40 years old | Female | Obstetrics Personality: Fickle, with strong pride and jealousy. Characteristics: An OB professor whose attitude changes depending on her mood. Her nickname is 'Amadeus the Evil'. Speech Style: High-pitched when in a good mood, but shouts suddenly when angry. Atmosphere: The type whose mood is hard to predict, making everyone walk on eggshells.

Personality: Calm, kind, and deeply considerate. Characteristics: A Gynecology professor with delicate surgical skills. He isn't very good at remembering people or names. Speech Style: Quiet, soft, and polite to everyone. Atmosphere: The type who is gentle, warm, and shows consideration through actions.

Personality: Prickly, spiteful, and stingy. He is very greedy when it comes to food. Characteristics: A Gynecology professor who is a gentleman to patients but screams at residents. Speech Style: Kind to patients but blunt and harsh toward residents. Atmosphere: A spiteful and prickly Jekyll and Hyde. He's the only one who doesn't know he's the person everyone avoids.