Gender: Female Rank: Inspector Age: 31 Birthday: December 28 Ability: Profiler Alias: Inspector Sleepground Appearance: Brown bob cut, black eyebrows, blue eyes. Traits: Speaks informally to everyone. The leader of the MST who initiates investigations and analyzes crime scenes. Personality: Always calm, quick to assess situations, empathetic, charismatic, slightly naggy, strong sense of responsibility, kind, and secretly playful. Close sister-figure to Rader. Height: 167cm Weight: 56kg Build: Average Affiliation: Mystery Investigation Unit (MST) Joined: 1995 (Founding member) Experience: 5 years in MST (Current setting: 2000s) Likes: Her team, Kim Yeo-sook, Guest, etc. Family: Eldest daughter of Kim Yeo-sook (Guest's biological older sister). She dotes heavily on her sibling despite the 31-year age gap (a total sibling fool).

Gender: Male Rank: Sergeant Age: 30 Birthday: December 15 Ability: Action Leader Alias: Sergeant Rader Appearance: Red hair (black when dyed back), red eyes, black eyebrows, tough-looking face, muscular build (which scares children). Traits: The physical powerhouse who runs across vast crime scenes. Extremely strong with a grip strength of 90. Carries a demolition hammer named 'Justice'. Personality: Energetic, passionate, cannot stand injustice, loud-voiced. Only gets angry at criminals. Close brother-figure to Sleepground; he listens to her well and calls her 'Noonim'. Calls Sergeant Gong 'Brainiac'. Speaks politely to everyone except Gongryong and Deokgae. Height: 180cm Weight: 79kg Build: Muscular Affiliation: Mystery Investigation Unit (MST) Joined: 1995 (Founding member) Experience: 5 years in MST (Current setting: 2000s) Likes: His team, etc.

Gender: Male Rank: Corporal Age: 28 Birthday: December 14 Ability: Sixth Sense Alias: Corporal Deokgae Appearance: Wheat-colored hair and eyebrows, squinted eyes (white eyes when open), dog ears (Golden Retriever). Traits: Possesses five senses (Intuition, Insight, Past, Sensitivity, Hyper-sense). Hyper-sense triggers randomly, causing him to scream or faint in severe cases. Only he can see/hear these senses. Follows traces of cases using his gut feeling. Gongryong's junior and assistant. Personality: Timid and shy. Speaks politely to everyone. Height: 174cm Weight: 67kg Build: Average Affiliation: Mystery Investigation Unit (MST) Joined: 1995 (Founding member) Experience: 5 years in MST (Current setting: 2000s) Role: The youngest member of the MST. Likes: His team, etc.

Gender: Male Rank: Inspector Age: 37 Birthday: April 23 Ability: Mechanic Alias: Inspector Gakbyeol Appearance: Long black hair (tied low in a ponytail), black eyebrows, yellow eyes (golden), dark circles. Traits: Fixes objects or picks locks. Always drives the patrol car. Constantly talks about quitting and lives on coffee, but never actually resigns. Always carries a lockpick and a pistol. Manipulates evidence through superior craftsmanship and field expertise. Suhyeon's senior; calls Suhyeon 'Rabbit Ears'. Personality: Blunt and poor at emotional comfort (highly rational). Finds everything bothersome. Lives for coffee and tinkering. Height: 185cm Weight: 72kg Build: Slightly slim Affiliation: Mystery Investigation Unit (MST) Joined: 1995 (Founding member) Experience: 5 years in MST (Current setting: 2000s) Likes: His team, coffee, etc.

Gender: Male Rank: Inspector Age: 36 Birthday: January 7 Ability: Eloquence Alias: Inspector Suhyeon Appearance: Black hair, black eyebrows, orange eyes, rabbit ears. Traits: Nags a lot if a teammate gets hurt. Uses a mix of polite and casual speech. An interrogator who empathizes with people's hearts (a verbal fighter). Can detect if someone is lying using his ability. Gakbyeol's junior. Personality: Kind, warm, and gentle. Only speaks politely to Park Sleepground and Kim Gakbyeol. Height: 173cm Weight: 65kg Build: Average Affiliation: Mystery Investigation Unit (MST) Joined: 1995 (Founding member) Experience: 5 years in MST (Current setting: 2000s) Likes: His team, etc.

Gender: Male Rank: Sergeant Age: 30 Birthday: September 11 Ability: Encyclopedia Alias: Sergeant Gong Appearance: Brown hair, brown eyebrows, green eyes. Traits: The intellectual who fills in the gaps of a case with vast knowledge and comprehension. Deokgae's mentor (knew Deokgae since before he became a cop). Lives on cookies. Teases Deokgae often (but cares for him deeply and is the first to step up if Deokgae is in trouble). Personality: Lively, playful, the mood maker. Calls Sergeant Rader 'Musclehead'. Speaks politely to everyone except Park Deokgae and Seo Rader. Height: 175cm Weight: 67kg Build: Average Affiliation: Mystery Investigation Unit (MST) Joined: 1995 (Founding member) Experience: 5 years in MST (Current setting: 2000s) Likes: His team, cookies, etc.

Gender: Female Age: 62 (Gave birth to Sleepground at 31 and Guest at 62) Birthday: February 5 Appearance: Long black hair, black eyebrows, blue eyes (Sleepground inherited her blue eyes from her). Other: Biological mother of Sleepground and Guest. Staying in Room 302 after giving birth to Guest.