He is notable for ranking first in the physical fitness test. He has lived as a neighbor to Sleepground since the past, to the point where they are like a younger brother and older sister.

In Season 1, Episode 6, a flashback through a family photo revealed that his current hairstyle is the result of hair dye and hard wax. His natural hair color is black, not red; in Episode 8, when he hadn't dyed it in time, he appeared with black hair with only the tips remaining red.

He mainly takes on the role of detection, using his superior senses to find hidden clues at crime scenes or pinpointing the location of investigations and the context of the story through clues learned from spirits and intuition. While his findings are often abstract and difficult to interpret, they frequently turn out to be core clues that pierce through the truth of the case. Rank: Sergeant, Gender: Male

He has the highest seniority and most experience among the members of the Mystery Investigation Unit. Perhaps because of this, he is proficient in many skills outside of his specialty. While he rarely leads the problem-solving as the main protagonist of a case, he is an all-rounder supporter who gets called in to help everywhere. Rank: Inspector, Gender: Male

In contrast to Rader, he is notable for ranking first in the written exam. He is also the only case who did not enter the investigation department directly but transferred from the General Affairs Department. Therefore, while his career as a police officer is longer than Deokgae's, his time in the criminal investigation department is roughly the same. Rank: Corporal, Gender: Male

A graduate of the Police Academy, she was appointed directly as an Inspector. After rotating through various positions, she was reassigned from Seokpa Police Station to Seonghwa Police Station on January 7, 1995. Before the formation of the investigation unit, she seems to have conducted investigations primarily alone and did not appear to have a very positive impression of team activities. Rank: Inspector, Gender: Female

Unlike the other detectives, he carries the additional title of Interrogator, and in-depth interrogations of suspects after a case are depicted as his responsibility. He appears to play a role similar to a team manager or secretary, such as selecting vacation destinations or reviewing external documents sent to the investigation unit. Rank: Inspector, Gender: Male

A total old-school hardhead who meddles in everything. He makes life miserable only for Guest. Gender: Male, Rank: Captain. He couldn't get married because he's such a busybody.