Seo Rather / Male / 29 years old / Sergeant (3rd year) Personality: Cheerful and righteous, yet possesses a serious side. Appearance: Red hair and red eyes (originally black hair), intimidating impression. Ability: Action Leader (Physical prowess, dash, physical analysis, reflexes, etc.) Traits: Rides a red motorcycle. Easily carries a demolition hammer named 'Justice'. Has known Sleepground since childhood; calls her 'Noonim' in private, though he gets scolded if he does so at work. A physical detective who excels in physical abilities and running across vast crime scenes.

Park Deokgae / Male / 27 years old / Corporal (5th year) Personality: Timid but passionate. Easily frightened. Appearance: Brown hair, squinted eyes, puppy ears, and a puppy tail. Ability: Sixth Sense (Superior five senses, spirits (intuition, past, sensitivity, insight, extrasensory perception), lingering thoughts). Traits: Parents died in a fire; lives with his grandmother. Junior to Gongryong. A dog beastman. A mysterious detective who tracks traces of cases with chilling intuition and gut feelings.

Kim Gakbyeol / Male / 36 years old / Lieutenant (3rd year) Personality: Laid-back and extremely lazy, but gets his work done. Appearance: Long black hair, golden eyes, handsome, severe dark circles. Ability: Mechanic (Mechanical engineering, lockpicking (Ttudda), marksmanship, autopsy). Traits: In charge of driving (Yellow SUV, though Rather refuses to ride in it). A caffeine addict who constantly talks about resigning. Was Soohyun's senior even before joining MST. A detective who manipulates traces of cases through exceptional dexterity and field gadgets.

Jung Gongryong / Male / 29 years old / Sergeant (3rd year) Personality: Energetic and mischievous. Occasionally serious. Appearance: Short brown hair, brown eyes, wears dinosaur-themed or green clothing. Ability: Encyclopedia (Hyperthymesia, intellectual curiosity, acquisition, conceptualization). Traits: Loves cookies. Senior to Deokgae. Grew up in poverty but became a police officer through sheer effort. An intellectual detective who fills the gaps in cases based on diverse knowledge and comprehension.

Park Sleepground / Female / 30 years old / Lieutenant (7th year) Personality: Calm with strong leadership. Quite kind. Appearance: Brown bob cut, gray eyes. Ability: Profiling (Reconstruction of events, hypothesis puzzles, logical reasoning). Traits: Leader of the MST. Close childhood friend to Rather. The authority of the investigation team who leads the start of investigations and analyzes the scene.

Hwang Soohyun / Male / 35 years old / Lieutenant (3rd year) Personality: Kind and calm, but incredibly eloquent. Appearance: Short purplish-black hair, orange eyes, rabbit ears, handsome rabbit-like face. Ability: Orator (Interrogation, psychological analysis, empathy, false debate). Traits: In charge of interrogations and nagging (especially towards Gakbyeol). An interrogator who empathizes with people's hearts through superior questioning skills.