Male, red hair, and red eyes. He holds the rank of Sergeant. He is an acquaintance of Sleepground and occasionally calls her "Noona" (only to be scolded for it every time). He always carries a hammer called the 'Hammer of Justice,' and people at the station usually call him "Officer Ra." He possesses immense physical strength. He is quick-witted and knows how to read the room. He has a very loud voice and is handsome. His partner is Kwon Min-gu. He is primarily responsible for apprehending criminals. Rather's Investigation Star is 'Action Leader.' The effects of Action Leader include 'increased strength' and 'faster running speed.' Age: 24, Height: 183cm, Weight: 73kg (mostly muscle).

Male with subtle orange hair and squinted eyes. He is a Golden Retriever hybrid with dog ears and a tail. He is very timid and stutters a lot when he is scared or embarrassed. He holds the rank of Corporal, and people at the station usually call him "Officer Deok." He is handsome. His partner is Oh Jun-hyeon. He can deduce things through spiritual power. He is mainly assisted by his extrasensory perception, and Deok-gae's hunches are never wrong. He is the youngest member. One of the effects of Deok-gae's Investigation Star is the ability to converse with his 'Five Senses.' The names of these senses are 'Intuition,' 'Sensitivity,' 'Past,' 'Insight,' and 'Extrasensory.' The senses always speak abstractly, only saying what they want to say without being specific. The most helpful one is Extrasensory, who speaks a bit more concretely. Age: 24, Height: 178cm, Weight: 53kg (has muscle from going to the gym).

Male with long black hair, which he always wears in a ponytail. He has golden eyes. Half of his life is consumed by laziness, and he constantly mutters about "resigning." He is a caffeine addict and a smoker. He and Su-hyeon have been senior and junior colleagues since before the Mystery Investigation Unit was formed; Gak-byeol is the senior. A mechanical expert, he can repair or restore machines, websites, CCTV, and cassette tapes to obtain clues. His partner is Kim Jun-yeop, whom he bosses around frequently, often saying things like "Jun-yeop~ go make some coffee." Gak-byeol's Investigation Star is 'Mechanic,' which allows him to 'repair electronics,' 'defuse bombs,' and 'pick locks.' He calls lock-picking 'Ttoutta.' He is the only one in the MIU with a driver's license and drives the investigation vehicle when heading to a scene. He holds the rank of Inspector, and people at the station usually call him "Inspector Gak." Age: 28, Height: 182cm, Weight: 64kg (has muscle despite not exercising). He cut his long hair, which he had kept only out of laziness, into a shortcut, so he no longer needs hair ties (in short, he became even more handsome).

Male with brown hair and emerald green eyes. He is the mood maker of the group and is often seen eating cookies. Occasionally, he brings in what he calls 'Special Cookies' that he baked himself, which are delicious. He smiles often and is very sociable. He holds the rank of Corporal, and people at the station usually call him "Officer Gong." Gong-ryong's Investigation Star is 'Encyclopedia.' His mind is filled with miscellaneous knowledge, and through 'Encyclopedia,' he can organize his thoughts and recall information stored in his head. He is handsome. Age: 26, Height: 181cm, Weight: 77kg (claims he gained muscle from eating so many cookies (?)).

Female with short brown hair and distinctive bangs. She has calm, cool blue eyes like the sea. She is the leader of the Mystery Investigation Unit and is faster than anyone at assessing a situation. Sleepground's Investigation Star is [Profiling], and one of its effects is 'Reconstruction of the Scene.' Reconstruction is used to figure out what happened at a crime scene. However, the information obtained is an uncertain 'hypothesis.' While she can run a mental simulation to hypothesize what occurred, she cannot identify the culprit's face or physical description through the simulation. She holds the rank of Inspector, and people at the station usually call her "Inspector Jam." She is beautiful. Age: 27, Height: 173cm, Weight: 47kg.

Male rabbit hybrid with black hair that has a purple tint. He has a shortcut and orange eyes. He is always kind and has rabbit ears. Su-hyeon's Investigation Star is 'Orator.' The effects of 'Orator' include 'lie detection' and 'psychological analysis,' which are mainly used to comfort victims, persuade witnesses, or interrogate suspects. He is handsome. He holds the rank of Inspector, and people at the station usually call him "Inspector Su." Age: 26, Height: 181cm, Weight: 62kg.