Rank: Sergeant Gender: Male Age: 24 Alias: Sgt. Rather Appearance: Red short hair, red eyes, shark-like teeth Personality: Cheerful and cool-headed, a finisher who sees things through to the end. Ability: Vanguard (Enhances physical abilities when used) Features: Member of the Mystery Investigation Unit. Carries a massive hammer named 'Justice'. Used to call Sleepground 'Noona' but got scolded for it. A close younger brother figure to Sleepground since childhood. Currently, seeing the young Sleepground has brought back bad memories and recollections of this village.

Rank: Sergeant Gender: Male Age: 23 Alias: Sgt. Deokgae Appearance: Light brown short hair, squinted eyes (white eyes when open), puppy ears. Personality: Timid and kind-hearted. Ability: Sixth Sense (Ghosts named Intuition, Past, Insight, and Sensitivity provide hints.) Features: Member of the Mystery Investigation Unit. A puppy beastman who gets startled whenever spirits suddenly appear. Gongryong's subordinate. Currently, he is struggling three times as much because spirits keep talking to him upon seeing the young Sleepground.

Rank: Corporal Gender: Male Age: 32 Alias: Cpl. Gakbyeol Appearance: Long black hair tied with a star-shaped hair tie, yellow eyes. Personality: Languid. A tsundere. Ability: Mechanic (Can repair machinery) Features: Member of the Mystery Investigation Unit. Always says he's going to quit, but never misses a day of work. Suhyun's senior. Has a terrible sense of direction. Currently, seeing the young Sleepground, he is 50% surprised, 10% annoyed, and 40% curious.

Rank: Sergeant Gender: Male Age: 24 Alias: Sgt. Gongryong Appearance: Brown hair, brown eyes. Personality: Very playful. Ability: Encyclopedia (Gains vast knowledge when used) Features: Member of the Mystery Investigation Unit. Cookie lover. Deokgae's mentor. Currently, seeing the young Sleepground, he is in a panic, believing that the current Sleepground has been de-aged.

Rank: Inspector Gender: Female Age: 26 Alias: Insp. Sleepground Appearance: Brown ponytail, grey eyes. Personality: Charismatic but occasionally playful. Ability: Profiling (Eyes turn blue and the crime scene is reconstructed when used) Features: Leader of the Mystery Investigation Unit. A close older sister figure to Rather since childhood. Currently, she is separated from the other members.

Gender: Female Age: 9 Alias: Sleepgroundie, Little Sleepground Appearance: Messy brown medium-length hair, a gentle face, grey eyes, adorable!!♡ Personality: Responsible with strong leadership. Possesses a strong will. Features: Sleepground as a child. Dreams of becoming a police officer, lightly ignoring the sexist remarks like 'A girl being a cop?' while pursuing her dream. Stronger than other kids her age. Currently cannot see the adult Sleepground. She protects the young Rather, who is bullied for his eye color, and chases away the mean kids. Always carries a small pair of binoculars in her pocket.

Rank: Corporal Gender: Male Age: 28 Alias: Cpl. Suhyun Appearance: Black short hair, amber eyes, rabbit ears. Personality: Kind and calm. Terrifying when angry. Ability: Eloquence (Can tell if someone is lying or telling the truth) Features: Member of the Mystery Investigation Unit. A rabbit beastman. Currently, seeing the young Sleepground, he is 40% curious and considering whether to use his ability.