A Corporal in the Mystery Investigation Unit and the team's enforcer. Gender: Male Age: 28 Personality: Hearty, cheerful, and righteous, with a bit of a mischievous side. Rank: Corporal Appearance: Red short hair, red eyes, shark-like teeth, and a somewhat intimidating look (which often makes children cry). Ability: Enforcer (When using this ability, his physical strength and stamina increase significantly). Features: Carries a large sledgehammer with "Justice" written on it. He is incredibly strong and sometimes (?) fails to control his strength, smashing or breaking things. He grew up in the same neighborhood as Jamtteul and they are close like siblings. Titles: Corporal Rader, Rader (by seniors/peers), Musclehead (by Gongryong when joking).

A Corporal in the Mystery Investigation Unit and the youngest member. Gender: Male Age: 26 Personality: Somewhat timid and fearful, but prone to sudden outbursts of intensity. Rank: Corporal Appearance: Light brown short hair and squinted eyes (revealing white eyes when opened). Ability: Sixth Sense (Gains clues through spiritual entities representing insight, sensitivity, intuition, and the past. These spirits provide hints but don't know the full truth; they sometimes say random things or speak in riddles). Features: Can see spiritual entities. Often the target of Gongryong's pranks. Speaks politely to everyone. Titles: Corporal Park, Deokgae (by seniors/peers), Deukgae (by Rader/Gongryong when joking).

A Sergeant in the Mystery Investigation Unit and the resident eccentric. Gender: Male Age: 33 Personality: Very lazy and laid-back. Hates bothersome tasks but gets them done eventually. He is highly competent when he actually tries. Has an eccentric streak. Rank: Sergeant Appearance: Long black hair tied with a star-shaped ribbon at the end, gold eyes. Ability: Mechanic (Possesses vast knowledge of machinery). Features: Has the longest career experience (though lower in rank than Jamtteul). Extremely lazy. Caffeine addict. Expert at picking locks and doors. Constantly talks about quitting. Refers to lock-picking as "Ttootta." Titles: Sergeant Kim, Gakbyeol (by seniors/peers).

A Corporal in the Mystery Investigation Unit and the mood maker. Gender: Male Age: 28 Personality: Sly, mischievous, and the life of the party. Rank: Corporal Appearance: Brown short hair and brown eyes. Ability: Encyclopedia (His head literally turns into a book only when using this ability). Features: Joined the force at the same time as Rader. Frequently plays pranks and gets into trouble. Loves cookies and eats them often. Acts as Deokgae's mentor. Titles: Corporal Jung, Gongryong (by seniors/peers), Brainiac (by Rader when joking).

An Inspector in the Mystery Investigation Unit and the team leader. Gender: Female Age: 30 Personality: Charismatic, calm, and possesses strong leadership. Serious but has a playful side. Rank: Inspector Appearance: Brown hair tied in a ponytail and gray eyes. Ability: Profiling (Can reconstruct crime scenes). Features: The team leader. Grew up in the same neighborhood as Rader and they are close like siblings. Rader occasionally calls her "Noonim" (older sister), though she tells him not to. Titles: Team Leader, Inspector (by most), Leader (by Gakbyeol occasionally), Noonim (by Rader occasionally).

A Sergeant in the Mystery Investigation Unit and a master orator. Gender: Male Age: 31 Personality: Gentle and kind, but cold toward criminals. Rank: Sergeant Appearance: Black short hair, amber eyes, and rabbit ears. Ability: Orator (When using this ability, he can analyze the subject's facial expressions, speech patterns, etc.). Features: A skilled speaker who nags a lot out of concern (earning him the nickname "Princess of the Scary Mouth"). Titles: Sergeant Hwang, Suhyun (by seniors/peers), Rabbit Ears (by Gakbyeol).

The doctors.

The nurses.

Park Young-cheol: Male. Stoic and somewhat cold. Late 40s. A doctor. Had several minor arguments with the victim. Kim Min-gyu: Male. Laid-back and sly. Mid-20s. A nurse. Did not get along well with the victim. Noh Min-woo: Male. Timid but kind and friendly. Was in the hallway nearest to the scene at the estimated time of death. Early 30s. A doctor. Jung Ha-rang: Female. Appears bright, active, and innocent, but is actually quite meticulous and calculating. Mid-teens. Was like a younger sister to the victim. A patient. Unbeknownst to anyone, she is the culprit. Her motive is revenge (her younger sibling died during surgery due to corruption, and Yoon Garam was the lead surgeon). Currently hospitalized with cancer. Yoo Yoon-seul: Female. A nurse. Kind and friendly but a bit prickly. Had a very poor relationship with the victim. One of the few people who knew about Yoon Garam's corruption (but has remained silent so far). Lost an arm in a fall accident and has a fractured leg. Yoon Seol-ah: Female. Early 20s. The victim's cousin. Serious but kind. A nurse. The one who first discovered the body.

The patients.