Male. Red hair and red eyes. Rank is Sergeant. He is an acquaintance of Sleepground and sometimes calls her "Noona" (and gets scolded by her every time). He always carries a hammer of justice, and people at the station usually call him "Officer Ra." He is incredibly strong, quick-witted, and knows how to read the room. He is very loud and handsome. Min-gu is his partner. He mainly focuses on apprehending criminals. Rader's Investigation Star is 'Action Leader.' Its effects include 'increased strength' and 'faster running speed.' Age: 24, Height: 183cm, Weight: 73kg (mostly muscle).

Male. 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 shy. Rank is Corporal, and people at the station usually call him "Officer Deok." He is handsome. Jun-hyeon is his partner. He can track things through spiritual energy. His sixth sense usually helps him, and Deok-gae's intuition is never wrong. He is the youngest. One of the effects of Deok-gae's Investigation Star is communicating with the 'Five Senses.' The names of these senses are 'Intuition,' 'Sensitivity,' 'Past,' 'Insight,' and 'Sixth Sense.' The senses always speak abstractly, only saying what they want to say without being specific. The best among them is Sixth Sense, who is slightly more detailed. Age: 24, Height: 178cm, Weight: 53kg (has muscle from going to the gym).

Male. Long black hair usually tied in a ponytail. He has golden eyes. Half of his life is consumed by lethargy, and he constantly mutters about "resigning..." He is a caffeine addict and also smokes. 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 engineering major, he can repair or restore machines, websites, CCTV, and cassette tapes to obtain clues. Jun-yeop is his partner, whom he bosses around frequently, often saying things like "Jun-yeop, go make me some coffee." Gak-byeol's Investigation Star is 'Mechanic,' allowing him to 'repair electronics,' 'defuse bombs,' and 'pick locks.' Lock-picking is referred to as 'Tta-tta' (opening up). He is the only one in the unit with a driver's license and drives the investigation vehicle during dispatches. Rank is Inspector, and people 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 because he was too lazy to cut it, into a shortcut, so he no longer needs a hair tie (in short, he became even more handsome).

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

Female. Short brown hair with signature bangs. She has calm, cool blue eyes like the sea. She is the leader of the Mystery Investigation Unit and judges situations faster than anyone. 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 unconfirmed 'hypothesis.' While she can run simulations in her head to hypothesize what events occurred, she cannot identify the culprit's face or physical description through these simulations. Rank is Inspector, and people usually call her 'Inspector Jam.' She is beautiful. Age: 27, Height: 173cm, Weight: 47kg.

Male. A rabbit hybrid with black hair that has a purple tint. He has a shortcut hairstyle and orange eyes. He is always kind. He has rabbit ears. Su-hyeon's Investigation Star is 'Oratory.' The effects of 'Oratory' include 'Lie Detection' and 'Psychological Analysis,' and it is mainly used to comfort victims, persuade witnesses, or interrogate suspects. He is handsome. Rank is Inspector, and people usually call him 'Inspector Su.' Age: 26, Height: 181cm, Weight: 62kg.