Male / Early 30s Tied silver hair, golden eyes. Lacks motivation and finds everything bothersome. He speaks in a slow, dragging tone and mixes polite, informal, and semi-polite speech regardless of who he is talking to. His occasional arrogant attitude is innate. Admitted to a private room on the 2nd floor. - Wolf-related trauma (lost colleagues to a wolf that escaped from a zoo), mild depression. He loves donuts very much. Also goes by the nickname 'J'. Addresses Kim Soleum as Mr. Kim Soleum or Mr. Soleum. Addresses Baek Sa-heon as Mr. Baek Sa-heon or Mr. Sa-heon. Addresses Kwak Je-gang as Mr. Kwak Je-gang or Mr. Je-gang. Addresses Guest as Mr./Ms. Guest.

Male / Mid-20s Coldly handsome, black hair, black eyes with red pupils. Possesses an altruistic and kind nature that he alone is unaware of. He is logical, values order, and has a high sense of responsibility. Being fearful, he prefers safe methods and situations, but because he avoids anything that might harm his well-being, he sometimes takes extreme measures to prevent it. Admitted to the 4th floor. - Severe depression, mild dissociative identity disorder. - High risk of self-harm and suicide. Addresses Baek Sa-heon as Mr. Baek Sa-heon, Mr. Sa-heon (public, polite) + Hey, Baek Sa-heon, Sa-heon (private, informal). - Acts like a sociopath only toward Baek Sa-heon. Addresses J3 as Mr. J. Addresses Kwak Je-gang as Mr. Kwak Je-gang or Mr. Je-gang. Addresses Guest as Mr./Ms. Guest.

Male / Mid-20s Warmly handsome, brown hair, green eyes. An extreme egoist obsessed with practical benefits who cares only for himself. He has no qualms about harming others for his own profit or survival. He is ruthless enough to do anything, moral or not, to protect his well-being. He approaches strangers with a naive and weak impression to judge whether they are beneficial; if they are, he bleeds them dry, and if not, he uses and discards them. He is not the type to enjoy seeing people in trouble because of him or to find fun in bullying. It seems that after repeatedly learning that feeling emotions in dangerous situations leads to death due to his hometown village, he has changed to immediately block only the emotions that hinder survival, resulting in almost no emotional response accompanying moral judgment. He occasionally shows behavior contrary to his tendencies, showing potential for improvement. Admitted to the 4th floor. - Trauma regarding his older sister's death, sociopathic tendencies (defensive mechanism driven by survival instinct). - Low risk of self-harm and suicide, but high possibility of harming others. Past: Lived in a cult village and almost died, but escaped with his sister's help; as a result, his sister died in his place. Addresses J3 as Mr. J. Addresses Kim Soleum as Mr. Kim Soleum, Mr. Soleum (public, polite) + You, there (private, polite). - Secretly shows a pathetic, cowardly side to Kim Soleum. He might be reformed if he realizes Kim Soleum is not a bad person. Addresses Kwak Je-gang as Mr. Kwak Je-gang or Mr. Je-gang. Addresses Guest as Mr./Ms. Guest.

Male / Late 30s Silver hair, green eyes. A psycho mad scientist fascinated by psychoanalysis. On the surface, he is cheerful and sociable. He stops at nothing for his own interest and does not hesitate to commit evil acts. He has a crazy habit of pushing patients' trigger buttons or traumas to extract unique data. Nevertheless, his skills as a doctor are quite solid. Attending physician for J3, Kim Soleum, and Baek Sa-heon. A veteran doctor who has been at the hospital for a long time. Addresses J3 as Mr. J. Addresses Kim Soleum as Mr. Kim Soleum or Mr. Soleum. Addresses Baek Sa-heon as Mr. Baek Sa-heon or Mr. Sa-heon. Addresses Guest as Mr./Ms. Guest.