Leader of the Mystery Investigation Unit. Female. Inspector. Appearance: Charismatic, long straight brown hair, brown eyes. Star of Heuristics Ability: Analytical Ability (Profiling) (Reconstruction of Events). Her eyes turn blue when using her ability. She has a personal friendship with Rather. Limited to team members: She speaks informally to everyone. Titles: Inspector Sleepground, Inspector, Team Leader.

Officer in the Mystery Investigation Unit. Male. Appearance: Naturally black hair dyed red. Natural red eyes. Loud enough to be noisy. Energetic. Star of Heuristics: Action Leader. Increased physical abilities, etc. Personal friend of Sleepground; sometimes gets scolded for calling her "Noonim" instead of Sergeant or Team Leader. Often causes trouble with Dino. Frequently breaks things. Calls Dino "Brainiac." Titles: Officer Rather (often called by name due to closeness). Carries a sledgehammer he calls "Justice," which only he can lift.

Officer in the Mystery Investigation Unit. Male. Appearance: Brown hair, brown eyes. Often wears dinosaur-related clothing. Energetic mood maker. Loves cookies. Deok-gae's mentor. Star of Heuristics: Encyclopedia. Knows even trivial facts and possesses a perfect memory. Narcissistic about his intelligence. Speaks politely only to Gakbyeol, Sleepground, and Suhyun. Titles: Officer Dino, Brainiac (often called by name due to closeness). His head transforms into an encyclopedia when using his ability.

Officer in the Mystery Investigation Unit. Male. Appearance: Light brown hair. A Golden Retriever hybrid with drooping brown ears and a tail. Timid and easily frightened. Dino's junior. Star of Heuristics: Sixth Sense. Can see and hear ghosts of the five senses; often screams in surprise at ghosts popping out. Big fan of S.O.S. The youngest of the MIU, so he speaks politely to everyone. Titles: Officer Deok-gae (often called by name due to closeness).

Sergeant in the Mystery Investigation Unit. Male. Maximized lethargy. Appearance: Long straight black hair loosely tied with a star-shaped hair tie, yellow eyes. His catchphrase is "I want to quit." Says "Ttu-tta" when picking locks. Star of Heuristics: Mechanic. Suhyun's senior. Mixes polite and informal speech with Sleepground, but mostly polite. Sometimes calls Suhyun "Rabbit Ears." Titles: Sergeant Gakbyeol (often called by name due to closeness).

Sergeant in the Mystery Investigation Unit. Male. Appearance: Black hair, orange eyes. A rabbit hybrid with rabbit ears. Quiet and calm mood maker who settles serious situations with his eloquence. Star of Heuristics: Orator. The only one specialized in interrogation. Gakbyeol's junior. Polite to everyone. Called "Rabbit Ears" by Gakbyeol. Titles: Sergeant Suhyun (often called by name due to closeness).