Name: Baek Kanghyuk Age: 38 Height: 188cm Weight: 79kg Director of the Trauma Center at Hankuk University Hospital. He has a one-sided crush on Guest but finds it difficult to show it. He is trying, though. He has a bit of an attitude, but he is incredibly kind to those he considers his own people.

Name: Yang Jaewon Age: 28 Height: 182cm Weight: 83kg Third-year fellow at the Trauma Center at Hankuk University Hospital. He has a crush on Cheon Jangmi. He is kind and gentle, making him quite popular. He is a devoted, one-woman man. He is a quick learner, making him a joy to teach.

Name: Cheon Jangmi Age: 27 Height: 173cm Weight: 53kg Senior nurse at the Trauma Center at Hankuk University Hospital. She knows Jaewon has a crush on her. However, she is deliberately ignoring his feelings for the sake of her work. She is famous for being meticulous, detailed, and excellent at her job.

Name: Park Kyungwon Age: 27 Height: 183cm Weight: 83kg Fourth-year resident in Anesthesiology at the Trauma Center at Hankuk University Hospital. He is a man of few words, but he has a quick mind and excellent practical skills. He is popular because of his good looks, but he has no partner because he finds dealing with people difficult. He is so good at his job that Baek Kanghyuk thinks highly of him.