Born as the late child of a nouveau riche family, she had a luxurious childhood. During her school years, she spent a gloomy adolescence as the all-around top student in the entire school, eventually clutching a 'medical school acceptance letter.' She is willful. From an uncontrollable mouth to a raw facial expression that she doesn't bother to manage at all—in short, she is a failure and unqualified for social life. She endured six years of medical school because her father promised to let her live independently, and she forced herself through her internship because he promised to open a clinic for her. The moment all of that went up in smoke, she left Jongno Yulje Hospital without a second's hesitation and wandered the hospital world as the subject of atrocious rumors. Now, that Oh Lee-young has returned to Jongno Yulje! And to the OB/GYN department, the one place she swore she'd never go! They say people don't change, and she is as consistent as ever. Her cynical and listless personality, living with a soulless 'Ah, I see' on her lips, remains the same. She has never had anything she wanted to own, anything she wanted to do, any desperation, patience, or persistence in her life. As always, she had the petty mindset of 'I don't care about others, let me just live my day well' and 'just endure it to get my paycheck.' But before she knew it, she started caring about the people in the Jongno Yulje OB/GYN department. Even as she grumbles her habit of saying "I won't do it! I can't! I'm quitting!", Lee-young heads to the hospital at 5:30 every morning with the most listless face in the world.

Living and dying for style! There is someone who treats the hospital lobby as a runway every morning. It's Pyo Nam-kyung, a first-year OB/GYN resident. She dyes her hair the latest trendy color at the salon, puts effort into her makeup for the short commute, and can't give up her luxury necklace even when wearing scrubs. But she thinks the coolest thing of all is 'me' in a white coat... ...or so she thought, but style be damned. One day was enough for all her fantasies and delusions to shatter. She thought she'd be a resident commanding the ward with her white coat fluttering... but in reality, she's busy pouting her lips to hold back tears at the sound of a mother's labor pains, a patient's groans, and the professor's scolding.

An idol who led K-culture at the center of the music industry for an era... well, not quite. He was a member of the group 'Hi-Boys,' who are a 'failed idol' to some and a 'Sugar Man' to others, having left behind exactly one hit song before a glorious defeat. His dancing, singing skills, and even popularity were always last in the team. However, thanks to his high IQ and excellent mental arithmetic, he became the 'ending fairy' of quiz programs rather than music shows. After the team disbanded, he utilized that personal talent to focus on his studies! He managed to enter medical school with great difficulty. He expected applause for being the 'first idol-turned-resident,' but all that was waiting for Jae-il was the title of 'last place' in everything he did.

A Superman who invariably appears whenever something happens and then vanishes into thin air, he is the guardian deity who practically lives at the hospital OB/GYN department. From professors to interns, everyone is constantly looking for Do-won, so his days pass in a blur. Because of this, all his actions are beyond fast—they are like lightning.

A 'Super AI' type human who would make 'Hi Bixby' cry, finding studying the easiest thing and textbooks the most fun in the world. No one expected that such a Sa-bi would become the biggest 'hole' among the first-years. Even though she memorized books and papers perfectly, she gets tongue-tied at patients' questions. Even when she explains things accurately according to the charts, mothers look at her as if they can't trust her at all. If there were a mistake, she could correct it; if she did something wrong, she could apologize... but since she doesn't know the reason, she can't do anything, and since she does nothing, she can't help but get scolded.

Older in spirit than the professors, she is known as a 'young kkondae' (young old-timer). She was just waiting for the day she could stop being the youngest in OB/GYN and show off her senior vibes to the first-years, but what on earth!! The 'nowadays' first-years are weirder than expected. Forget showing respect to seniors like she did! These kids nowadays are far too slack. And that's not all! She's already struggling just to handle the titles of 'second-year' and 'senior,' and she wonders if they even realize how she feels...

A possessor of 'sweet and salty' charm who is a wicked witch in March but becomes the 'Professor of the Year chosen by residents' in December. With the most patients, surgeries, and outpatient appointments at Jongno Yulje, she is the young professor currently receiving the most attention in the obstetrics department. One of the things Jung-min puts her heart and soul into is resident training. She scolds residents until they cry with bone-chilling words for their mistakes, only to feel a bit sorry as she turns away and looks for a way to make it up to them. Even so, if a response to her question is even a second slow, she transforms into a 'question mark killer' who pours out follow-up questions until the residents are utterly sick of it.