- Age: 37. Tall and handsome. A man of cool judgment and a strong sense of responsibility. He is usually soft-spoken and doesn't show his emotions easily, but he is more affectionate and devoted than anyone else to those he loves. He remains calm and finds solutions even in crises. When angry, his tone turns cold, but he never acts purely on emotion. The star doctor of Woori-Hamkke Hospital. If you search for the hospital online, Tae-ju's face appears before the director's. His surgical skills are as famous as his name, and he is considered a top expert in spinal nerve microsurgery. He has a firm conviction as a doctor to always prioritize the patient. His relationship with his wife, Ko Se-yun, the hospital's board chair, soured long ago due to a certain incident, leading him to decide on a divorce. One night, while drunk, he blurts out to Noh Man-hee that he wants his wife 'gone,' and when that unexpected request becomes a reality, he finds himself at the center of all suspicion.

- Age: 35. Tae-ju's wife. Born as the only daughter of a doctor father and a mother with a PhD in business administration, she grew up wealthy. She graduated from the same medical school as Tae-ju, but currently serves as the board chair of Woori-Hamkke Hospital, focusing on hospital management. She is a workaholic who cannot let go of work even at home. At some point, she began living off the strength of her resentment and hatred for her husband. Sometimes she thought she was being unreasonable, but she couldn't endure without getting angry. She even received advice that it would be better to just break up. She has now been kidnapped by Noh Man-hee.

- Age: 42. Possesses an ordinary appearance that is hard to remember at a glance. He has earned a good reputation among students and neighborhood elders for his kind speech and attitude. One day, Man-hee appeared as Tae-ju's designated driver while Tae-ju was drunk and kidnapped Se-yun. He begins to demand a large sum of money, claiming that Tae-ju is the cause of all this. His voice over the phone is polite, and his tone is even sweet. However, if the other person defies his will even slightly, he explodes instantly. He seems to harbor a grudge against Woori-Hamkke Hospital. He lives in a large warehouse deep in the mountains. It appears to have originally been a restaurant.

- Age: 39. A mysterious woman who suddenly appears before Se-yun in her moment of distress. Her words and actions are certainly kind, but there is a strange sense of dissonance about her. Her appearance, which seemed like a coincidence, leads the incident in an unimaginable direction. (In fact, she is Noh Man-hee's accomplice and his wife.) She speaks in a dialect.

Mid-60s. Se-yun's father. An authority in the field of neurosurgery and the spine. The founder who built Woori-Hamkke Hospital into what it is today. He is a kind father to Se-yun, but he is always a difficult and uncomfortable father-in-law to Tae-ju. Although his daughter has been kidnapped, Dong-chan's reaction is peculiar. Behind the image of an angry and worried father, there seems to be another hidden agenda. Perhaps he is afraid that this incident will be linked to his own secrets.

- Age: 37. Tae-ju's medical school classmate and hospital colleague. Since they have known each other for a long time, they know each other's circumstances inside and out, making him the only friend Tae-ju confides in. With a gentle personality, he often takes on the role of mediating conflicts within the hospital.