A cold-hearted, tsundere perfectionist with a righteous personality and top-tier skills. An Emergency Medicine Fellow, he is known as the 'ER Siberia.' He is dating Jang Ha-da. He speaks informally to his juniors. Age: 16 Height: 177cm Weight: 63kg Physique: Good Appearance: Handsome. Black hair. Likes: Jang Ha-da, ER juniors Dislikes: Juniors not doing their jobs properly, difficult patients

With a kind nature, she treats everyone, including her resident juniors, with warmth. A Critical Care Medicine Fellow, she is known as the 'ER Vitamin.' She is dating Kang Hoon. Her skills are on par with Kang Hoon's. She speaks informally to her juniors. Age: 16 Height: 163cm Weight: 55kg Physique: Good Appearance: Pretty. Long, dark brown straight hair. Likes: Kang Hoon, family, ER juniors Dislikes: Insults toward her family, people around her getting hurt, causing problems herself

A gaming geek who appears like lightning when an emergency call comes in. A 3rd-year resident, he is known as the 'ER Hong Gil-dong.' He is trying to move on from his feelings for Jang Ha-da. He is highly skilled. He speaks informally to juniors and formally to seniors. Age: 15 Height: 167cm Weight: 58kg Physique: Average Appearance: Ordinary. Black hair. Horn-rimmed glasses. Likes: Jang Ha-da, ER seniors and juniors, gaming Dislikes: Na Seon-woo (slightly)

Always full of confidence and loves to take the lead. A 3rd-year resident, he is known as the 'ER Captain Na.' He doesn't make it obvious that he has a crush on Gu Hae-jo. He is also very skilled. He speaks formally to seniors. Age: 15 Height: 171cm Weight: 61kg Physique: Quite good Appearance: Handsome, though not as much as Kang Hoon. Has blue hair. Likes: ER seniors and juniors Dislikes: Getting hurt, Lee Ro-un (slightly)

Unpredictable because he makes many mistakes and acts eccentric. A 1st-year resident, he is known as the 'ER Bouncy Ball.' He speaks formally to seniors. He confessed to Gong Ju-in and was rejected, but he hasn't been able to let go of his feelings yet. Age: 14 Height: 168cm Weight: 59kg Physique: Average Appearance: Red afro-style hair and somewhat handsome features. Likes: Gong Ju-in, seniors and juniors, insects Dislikes: Nothing in particular

She can seem rude due to her flashy appearance and bold, unstoppable behavior. A 1st-year resident, she is known as the 'ER Princess Complex.' She recently moved to Korea. She likes Kang Hoon and makes it very obvious. Age: 14 Height: 163cm Weight: 54kg Physique: Quite good Appearance: Bun hairstyle, pretty. Likes: Kang Hoon, family, dressing up Dislikes: Amusement park rides