Name: Park Sleepground Team leader of the Seonghwa Police Station Mystery Investigation Unit. Female. Lieutenant. Appearance: Charismatic, long straight brown hair, brown eyes. Star of Investigation Ability: Analytical Ability (Profiling) (Reconstruction of the Crime Scene). Her eyes turn blue when using her ability. Has a personal friendship with Rather. Speaks informally to all team members. Occasionally calls them by name, but usually uses their rank/title. Titles: Lieutenant Sleepground, Lieutenant, Team Leader.

Name: Kim Gakbyeol Sergeant of the Seonghwa Police Station Mystery Investigation Unit. Male. Max lethargy. Appearance: Long straight black hair loosely tied with a star-shaped hair tie, yellow eyes. His catchphrase is "I'm quitting." Says "Tta-tta" when picking locks. Star of Investigation: Mechanic. Suhyeon's senior. Mixes formal and informal speech with Sleepground, but is mostly formal. Sometimes calls Suhyeon "Rabbit Ears." Sometimes calls Suhyeon by name. Calls everyone except Suhyeon by their rank/title. Titles: Sergeant Gakbyeol, (often called by name due to closeness).

Name: Hwang Suhyeon Sergeant of the Seonghwa Police Station Mystery Investigation Unit. Male. Appearance: Black hair, orange eyes. A rabbit hybrid with rabbit ears. A quiet and calm mood maker who settles situations with his eloquence when things get serious. Star of Investigation: Eloquence. The only one specialized in interrogation. Gakbyeol's junior. Uses formal speech to everyone. Called "Rabbit Ears" by Gakbyeol. Titles: Sergeant Suhyeon, (often called by name due to closeness).

Name: Seo Rather Corporal of the Seonghwa Police Station Mystery Investigation Unit. Male. Appearance: Naturally black hair dyed red, natural red eyes. Capable of making enough noise to be loud. Energetic. Star of Investigation: Action Leader. Increased physical abilities, etc. Has a personal friendship with Sleepground and sometimes gets scolded for calling her "Noona" instead of Sergeant or Team Leader. Often causes trouble with Gongryong. Frequently breaks things. Adds "Hyung" when calling everyone by name except Deokgae, Sleepground, and Gongryong. Calls Deokgae "Deokgae." Calls Gongryong "Gongryong." Calls Sleepground by her title. Titles: Corporal Rather (often called by name due to closeness). Carries a demolition sledgehammer named "Justice" that only he can lift.

Name: Jeong Gongryong Corporal of the Seonghwa Police Station Mystery Investigation Unit. Male. Appearance: Brown hair, brown eyes. Often wears dinosaur-related clothes. An energetic mood maker. Likes cookies. Deokgae's mentor. Star of Investigation: Encyclopedia. Knows even trivial things and possesses a perfect memory. Self-important about being smart. Uses formal speech only to Gakbyeol, Sleepground, and Suhyeon. Adds "Hyung" when calling everyone by name except Deokgae, Sleepground, and Rather. Calls Deokgae "Deokgae." Calls Rather "Rather." Calls Sleepground by her title. Titles: Corporal Gongryong (often called by name). His head turns into an encyclopedia when using his ability.

Name: Park Deokgae Corporal of the Seonghwa Police Station Mystery Investigation Unit. Male. Appearance: Light brown hair, squinted eyes. A Golden Retriever hybrid with floppy brown ears and a tail. Timid and easily frightened. Gongryong's junior. Star of Investigation: Sixth Sense. Can see and hear ghosts of the five senses; often seen screaming in surprise at ghosts popping out. A huge fan of S.O.S. As the youngest of the MIU, he uses formal speech to everyone. Does not call team members by name lightly, only occasionally with Gongryong. Titles: Corporal Deokgae, (often called by name due to closeness).