1st-year OB/GYN Resident Personality: A cynical and aloof character who lives with soulless reactions like "Oh, I see." Due to her uncontrollable tongue and blunt facial expressions, her social skills are at a failing grade, but when dealing with patients, she offers more sincere comfort than anyone else and possesses a bold side that doesn't tolerate injustice. In romance, she is a 'full-throttle' style who dashes forward with direct hits without hesitation. Family: Born into a nouveau riche family, she has an older sister, Oh Ju-yeong. Since Gu Do-won's older brother (Gu Seung-won) became her sister's husband (brother-in-law), she and Gu Do-won are related by marriage. Gender: Female Age: 28

1st-year OB/GYN Resident Characteristics: The daughter of a famous mandu restaurant who grew up wanting for nothing, she is the ultimate fashionista. She is the type who would give up sleep before giving up a full face of makeup. Personality: Possesses a fresh and cheerful charm. She dreamed of being a doctor who coolly commands the ward, but she grows as she experiences the gap between the ideal and the harsh reality where she feels insignificant. Gender: Female Age: 28

1st-year OB/GYN Resident Characteristics: Has a unique background as a former idol member. After the group 'High Boys' disbanded, he studied fiercely to enter medical school. Personality: Being a former idol, he expected glamorous attention from the world, but in reality, he is the last-place resident who barely got in due to a shortage in the OB/GYN department. Although he worries because things get tangled up, he shows a hardworking and persistent nature, splitting his time to ask questions and run around. Gender: Male Age: 28

1st-year OB/GYN Resident Characteristics: The top elite resident of Yulje Hospital who took first place all the way through the national medical licensing examination. Personality: A 'genius doctor' who seeks perfection and has no gaps when it comes to study and work. However, she undergoes growing pains, realizing through unpredictable situations encountered in actual hospital life that theory isn't everything. Gender: Female Age: 28

Characteristics: A 4th-year resident and the primary romance interest who captures Oh I-yeong's heart. He is the brother of Oh I-yeong's brother-in-law. Personality: A sweet and affectionate personality in every way. He silently accepts and takes care of the rough and uncontrollable Oh I-yeong. His representative official nicknames are 'Class President Gu', 'Gu-God', 'Gureung-dowon' (Peach Blossom Spring), and 'Hogu-dowon' (Pushover Gu). Gender: Male Age: 33

Characteristics: The core star professor of the Obstetrics department at Jongno Yulje Hospital with the highest number of expectant mothers, surgeries, and outpatients. She leads a busy life surviving on mix coffee because she has no time to go to a cafe. Personality: In the beginning of March, she is known as the 'Wicked Witch' for harshly training the residents, but by December, she is a mentor with a clear 'sweet and salty' charm, being named 'Professor of the Year' by the residents for deeply caring for her students behind the scenes and raising them into proper doctors. Gender: Female

Characteristics: An Obstetrics professor who was a medical school classmate and rival of Professor Seo Jeong-min. An unpredictable figure whose mood the OB/GYN residents must check first as soon as they clock in. Personality: When her mood is at its peak, she is a warm-hearted person who takes care of her juniors' breakfast with a high-toned voice, but when she is in a bad mood, she screams and snaps at the smallest things, earning her the nickname 'Amadeus of Evil'. She has a jealous and human side, seething internally while watching her classmate Seo Jeong-min succeed as the hospital's face or senior Professor Im Dong-ju being praised as a 'God'. Gender: Female

Characteristics: The Obstetrics professor who approaches the residents in the most friendly and accessible way. Personality: He has a deep love for his juniors and a kind, righteous character. He acts as a reliable shield for his students, such as standing up and speaking out loudly to protect and represent 1st-year resident Kim Sa-bi when she is unfairly and wrongly scolded by another professor. Gender: Male

Characteristics: In charge of Gynecology at Jongno Yulje Hospital, he is the most feared figure by residents and a professor who reaches the peak of strictness. Personality: With a strong principled nature, he is a meticulous and harsh character who does not tolerate even small mistakes or gaps in hospital life or the operating room. He is a figure of terror who kills the spirit of the elite resident Kim Sa-bi, who is perfect in theory but clumsy in practice, by shouting at her mercilessly, but he is a stern teacher who makes the residents tense enough to reduce their mistakes. Gender: Male

Obstetrics Fellow (2nd year) Characteristics: During her time at the main hospital, she pushed all sorts of annoying tasks and chores onto her classmate Chu Min-ha while focusing only on looking good to the professors. However, when none of the professors at the main hospital offered her a fellow position and only looked for Chu Min-ha, she felt twisted inside and applied to Jongno Yulje as if fleeing. She vows to get the title of professor before Chu Min-ha at Jongno Yulje, but her villainous behavior remains the same even at a different hospital. She even committed the atrocity of stealing Gu Do-won's thesis to take the top prize at a conference presentation. Personality: On the outside, she smiles and pretends to be bright and kind, but on the inside, she is a deeply selfish and cunning 'fox-like human' and the representative villain of the OB/GYN department. She is the epitome of 'strong against the weak, weak against the strong,' pestering and unfairly exploiting the 1st-year rookie residents. Gender: Female