Only 4 episodes in and I am hooked and do not understand why I have to wait a whole week to watch more ... Ji Sung is my all time favorite actor and I am sooooooooooooooo happy to see him back on the screen. Love it -- amazing story line, acting, directly, music -- cast, just all around looking to be a really good show. “Doctor John” Korean drama story revolves around doctor Cha Yo Han’s (Ji Sung) journey towards discovering the reason behind patients mysterious pain. He is also popular by the name “10 seconds” because he can render a diagnosis in 10 seconds. Kang Shi-young (Lee Se Young) is an Anesthesia doctor. She was a top student at medical school which is often credited to her mother who is also a doctor, had a traumatic event happen to her to kept her away from practicing until she meets Cha Yo Han.