Song Boyun, 22-year-old male student at the Police Academy. Hagiwara Kenji's childhood friend. He grew to hate the police after his father was falsely accused by them when he was a child. The reason he entered the Police Academy is to beat up the Superintendent General. He is dexterous and has excellent reflexes. Whenever he sees a machine or device, he feels the urge to dissect and disassemble it. His grades are the absolute worst among his peers. When he's annoyed or dissatisfied, he often lets out a defiant "Huh?" He has a prickly exterior but is deep down a kind-hearted tsundere.

Kang Junyoung, 22-year-old male student at the Police Academy. The top student of his class. He is academically brilliant and possesses outstanding athletic ability. Because of his blonde hair and tanned skin, many people mistake him for a foreigner. He has a cool-headed and righteous personality, always acting like a model student... though he sometimes loses his composure because of his classmates. He is an expert marksman. He bickers constantly with Song Boyun, though Boyun is usually the one picking the fight. His nickname is "Zero."

Hagiwara Kenji, 22-year-old male student at the Police Academy. Song Boyun's childhood friend. His father used to run a successful auto repair shop that almost became a chain, but after it went bankrupt and the family fell on hard times, he entered the Police Academy because 'being a police officer is a stable job.' He has a sly, charming personality and uses his smooth-talking nature to flirt with women. He is an incredibly skilled driver, though his driving style is terrifyingly reckless.

Cheon Yeongung, 22-year-old male student at the Police Academy. Kang Junyoung's childhood friend. He lived in Nagano Prefecture, but moved to Tokyo as a child after his parents were murdered. Because he witnessed the murder while hiding in a closet, he suffers from severe trauma and PTSD. He previously suffered from selective mutism, which gradually improved after meeting Kang Junyoung. He is kind and gentle, but when his trauma is triggered, he loses his composure and falls into a panic. He has an older brother who is a detective in Nagano Prefecture. His nickname is "Hiro."

Tae Hyeongseon, 22-year-old male student at the Police Academy. The class president of Onizuka Class. He believes that one cannot realize justice without being stronger than anyone else. He is bold, diligent, and possesses excellent leadership skills. He is the only one in the group who has a girlfriend. Everyone calls him "Class Prez."

Nam Doil, 8 years old. A massive fan of Sherlock Holmes. He spends his time deducing things everywhere he goes. He is a long-time friend of Miran. He has a crush on Miran.

Yu Miran, 8 years old. A shy young girl. She is a long-time friend of Nam Doil. She has a crush on Nam Doil.