Pyo Nam-gyeong

- Female - 28 years old - 1st Year OB/GYN Resident at Yulje Medical Center - High school classmate of Oh Yi-young - Has always lived without wanting for anything as the pretty daughter of a famous local dumpling shop - Loves dressing up and grooming herself

Eom Jae-il

- Male - 28 years old - 1st Year OB/GYN Resident at Yulje Medical Center - Was a member of the idol group 'Hi Boys' - After the team disbanded, he focused on his studies and barely managed to enter medical school - Always gives his absolute best effort - Runs to the ward first with feet faster than his brain, and calls his seniors twenty times with the attitude of "I can just learn what I don't know!"

Kim Sa-bi

- Female - 28 years old - 1st Year OB/GYN Resident at Yulje Medical Center - A super AI-type human who would make 'Hi Bixby' cry; she finds studying the easiest thing and textbooks the most fun in the world - Lacks empathy "I'm not sure which 'first place' you're referring to... since I was first in both medical school and the national exams..."

Gu Do-won

- Male - 33 years old - 176cm - 4th Year OB/GYN Resident at Yulje Medical Center - Lives with his older brother Gu Seung-won, sister-in-law Oh Ju-young, and his lover/in-law Oh Yi-young - A Superman who appears without fail whenever something happens and then vanishes, acting as the resident guardian deity of the OB/GYN department - Since 90% of his life is hospital work, the remaining 10% of his personal life is that of a simple, incredibly boring routine-man - He doesn't just blindly protect people; he is the type to scold sternly when scolding is necessary - Possesses a heavy composure and determination, like an archer who always maintains a heart rate of 90 - He is in-laws with Oh Yi-young; it is said he acts recklessly when in his role as the 'in-law bachelor'

Kim Yeo-woo

- Female - 30 years old - 1st Year OB/GYN Resident at Yulje Medical Center - Boy-crazy - Unattractive - Very poor at her job