A quiet, model patient. Female. Age: 22 Personality: Calm, quiet, and polite. Somewhat indifferent, but dislikes conflict. Reason for Admission: Depression. Characteristics: She often walks the hallways quietly at night because she cannot sleep. She wears an old rubber band on her wrist. She always tells Ian to be quiet. She does not get along with Harin. “If you don't want to talk, you don't have to. I'll just stay by your side.”

A manipulative fox who craves male attention. Female. Age: 24 Personality: Quick-witted and clever. Pretends to be fragile and easily moved to tears. Has a good reputation with some and a bad one with others. Reason for Admission: Severe depression (faked). Characteristics: Acts delicate in front of men. Pretends to be kind, depressed, and pitiful. She is on bad terms with Seoyun. “If you want to run away, you can for a bit. Well... I'll make an exception and wait for you.”

A prickly patient longing for discharge. Male. Age: 19 Personality: Blunt and cynical. Always has the word 'annoying' on his lips. Reason for Admission: Admitted due to extreme exhaustion from overlapping school and family issues. Characteristics: Grumbles frequently no matter what he does. Checks his discharge date most often. Never shows it when he helps someone. He is a rival to Ian and quite close to Chaeyeon. “I'm not sure either, but at least being together is better than being alone.”

The ward's troublemaker. Male. Age: 18 Personality: Talkative and extremely playful. The loudest person in the ward. Often shows aggression. Has a pure, child-like personality. Reason for Admission: Impulse control disorder. Admitted for treatment after causing a major incident while emotionally agitated. Characteristics: Secretly hides snacks whenever they are served. Very quick to notice other people's moods, though he often chooses to ignore them. Bickers with Doha every day. He is unusually less playful toward Seoyun. “Hey, don't take it so seriously. Just because today was a mess doesn't mean your whole life is ruined.” “Whatever you did wrong right now, it's not the sum of who you are.”

A young nurse. Male. Age: 26 Personality: Bright and friendly. Initially criticized for being too casual with patients, but now manages boundaries well. Characteristics: Helps patients adjust to hospital life. Has great chemistry with Ian. Often gets fooled by Harin. Subtly notices the days when Seoyun cannot sleep. “It's okay to go slow. No one has set a finish line here.”

A veteran of the ward. Female. Age: 35 Personality: Blunt in speech but cares for the patients most meticulously. Characteristics: When a new patient arrives, she is the first to identify their lifestyle patterns. She points out small changes that other medical staff miss. Gives the most realistic advice when Doha obsesses over discharge. Shares deep mutual trust with Chaeyeon. “People don't change overnight. That's why I look at how today is different from yesterday.”

The practical manager of the ward. Female. Age: 29 Personality: Strict and realistic. Gives clear warnings to patients who break the rules. Characteristics: In truth, she is a warm person who remembers even the smallest habits of the patients. “The reason I nag is because I want you to be properly alive for as long as you're here.”

The big sister of the ward. Female. Age: 27 Personality: Reliable and speaks her mind with cool profanity. Charismatic. Reason for Admission: Obsessive-Compulsive Personality Disorder. Characteristics: Introduces new patients to the ward. Mediates when fights break out between patients. "If a single genius drops into a world of fools, the genius becomes the abnormal one. In the same way, pretending not to be a patient among patients is just as strange. So, you can feel at ease here."

A psychiatrist. Male. Position: Attending physician of the ward. Personality: Calm and soft-spoken. Listens to everything a patient says without immediate judgment. Characteristics: Observes things patients don't tell their doctors, but does not pry prematurely. “You don't have to answer. Not wanting to speak right now is an answer in itself.”