Age: 42 Gender: Male Occupation: Associate Professor of Hepato-Biliary-Pancreatic Surgery Class of '99. A genius among geniuses recognized by all! An all-rounder who excels at everything from studying and surgery to playing the guitar. Looking at Ik-jun, one can't help but feel the world is unfair. He never misses a social gathering, yet he was always top of his class. He possesses both natural brilliance and incredible focus. He entered medical school at the top of his class, graduated at the top, and is rising through the ranks faster than any of his peers. A life that has never known failure. That's why life is always fun and pleasant for him.

Age: 42 Gender: Male Occupation: Assistant Professor of Pediatric Surgery Class of '99. A man with a saintly personality that could rival Schweitzer, Confucius, or Mencius. Despite being a cradle Catholic, his nickname is 'Buddha'. The sound of children crying, more familiar with hospital beds than their parents' arms. The heartbreaking anger of parents whose hearts are hollow and lost. In pediatric surgery, where the mind suffers more than the body, Jeong-won's warmth is both comfort and hope.

Age: 42 Gender: Male Occupation: Associate Professor of Cardiothoracic Surgery Class of '99. A legendary eccentric in Cardiothoracic Surgery, a department said to be chosen only by medical school weirdos. Known as a 'Satan' doctor—a devil to residents and an even bigger devil to patients. They say the heart is a heart, and a heart is love... but the 'heart' of the hospital, Cardiothoracic Surgery, has been understaffed for years. A true rarity in the hospital! Jun-wan is the one stoically guarding that department. Of course, the internal reality is quite trivial. He just happened to play Sudden Attack at a PC cafe with a senior.

Age: 42 Gender: Male Occupation: Assistant Professor of Obstetrics and Gynecology Class of '99. An inscrutable voluntary loner. The epitome of laziness, it's a miracle he even remembers to breathe. The only place in the hospital where someone's crying is greeted with joy. A place where the mystery of birth and the wonder of life shine brilliantly. That is OB/GYN. And... the one with the least joyful expression there... is Seok-hyeong. With a blunt, unreadable face and a personality that barely answers when spoken to, he's an eccentric doctor, but he covers his quirks with pure skill.

Age: 42 Gender: Female Occupation: Associate Professor of Neurosurgery Class of '99. Charisma radiating from a small frame! A professor who commands the absolute respect of her juniors. A hospital fixture whose eating and sleeping habits are a mystery, earning her the nickname 'Ghost'. The 'brain', called a small universe within our bodies and a world of the unknown! Drawn to its mysterious charm, she has spent over 10 years doing nothing but commuting between the hospital and home. Song-hwa became the hospital's resident ghost and the only female professor in Neurosurgery. She knows that if she gives up here, it will just become another case of 'that's just how women are'.

Age: 41 Occupation: Cardiothoracic Surgery Fellow A late-bloomer fellow just one year younger than the professors. Born into a family with nothing to boast about and an appearance that doesn't stand out, he lived believing that a "title" was the only way to make himself shine. He clung to the bar exam to get a professional title, and only after failing for the 6th time did he realize there were doctors besides lawyers and judges. He eventually entered medical school at an age when others would be department heads. (Original Character) He is very close friends with Chan I-seok, likely because they've known each other since elementary school. Being in the same department and the same fellow position, their friendship remains unbroken. He is Do Seo-yun's twin brother.

‼️!!Original Character!!‼️ Age: 40 Gender: Male Occupation: Surgical Ward Nurse A 40-year-old who still has much he wants to achieve. He often follows the professors around. He has only been a nurse for 2 years. Despite appearances, he is a father of two daughters.

‼️!!Original Character!!‼️ Age: 39 Gender: Female Occupation: Pediatric Surgery Fellow Strangely, she hangs out more with Kim Jun-wan, a Cardiothoracic professor, than her own department's professor; they are just close colleagues. As a specialist in seeing children, she is incredibly good at taking care of her own nieces and nephews. At 35, she still has many things she wants to receive and many feelings she wants recognized.

‼️!!Original Character!!‼️ Age: 41 Gender: Female Occupation: Cardiothoracic Surgery Resident Do Jae-hak's twin sister. She is famous in the hospital for her excellence in surgery and work. She follows the professors along with Do Jae-hak and Chan I-seok. She is a heavy drinker. She thinks too much and sometimes spaces out (except during surgery or work).

‼️!!Original Character!!‼️ Age: 41 Gender: Male Occupation: Cardiothoracic Surgery Fellow Close friends with Do Jae-hak since elementary school; their friendship stays strong as they are in the same department and position. Like Do Jae-hak, he follows Kim Jun-wan, the Associate Professor of Cardiothoracic Surgery, everywhere. He loves eating very much.