A member of the Security Bureau, Security Planning Division (Public Security Bureau) of the National Police Agency, often referred to by the codename "Zero," signifying a non-existent organization. During his time at the Police Academy, he was a legendary cadet who entered as the top of his class with straight A's in all subjects. He belonged to the Onizuka class and was classmates with Jinpei Matsuda, Kenji Hagiwara, Hiromitsu Morofushi, and Wataru Date. His record of straight A's is unprecedented in the academy's history. While serious and possessing a strong sense of justice, his conspicuous blonde hair often led to conflicts with other students. Hiromitsu Morofushi is his childhood friend. He initially clashed with Jinpei Matsuda, but they eventually came to respect each other. His motive for becoming a police officer was to find Elena Miyano, who went missing.

A member of the Explosive Ordnance Disposal (EOD) squad within the Security Department's Mobile Unit. During his academy days, he was a classmate of Rei Furuya, Jinpei Matsuda, Hiromitsu Morofushi, and Wataru Date. His older sister, Chihaya Hagiwara, is a motorcycle police captain. He is a social, gentle, big-brother figure who naturally picks up on people's feelings. In contrast to Jinpei Matsuda, he is always considerate of those around him. He has high insight and is skilled at reading people's expressions. While active in social mixers, he cannot leave someone in trouble alone. He has built a strong bond of trust with Furuya, Matsuda, Date, and Morofushi.

A member of the Explosive Ordnance Disposal (EOD) squad within the Security Department's Mobile Unit. During his academy days, he was a classmate of Rei Furuya, Kenji Hagiwara, Hiromitsu Morofushi, and Wataru Date. He lacks cooperativeness and is quick to pick a fight, but his skills in bomb disposal and mechanics are genius-level. He was labeled as part of a "troublesome bunch" by instructors for things like disassembling his handgun without permission. He aspired to be a police officer because his father, a former professional boxer, was wrongfully arrested; he wants to correct that warped system and punch the top of the police force (the Superintendent General) to clear his head. Despite hating the police, he entered the academy for that goal. He initially got into fistfights with Furuya but eventually became a trusted, high-skill troublemaker. He is especially close to Hagiwara.

A member of the Tokyo Metropolitan Police Department Public Security Bureau. During his academy days, he was a classmate of Rei Furuya, Kenji Hagiwara, Jinpei Matsuda, and Wataru Date. He has a cheerful, kind, and serious personality. He is good at playing the guitar. While ordered to clean the baths by Instructor Onizuka, he becomes involved in a missing person case of a girl he met in the past. Additionally, with the help of his friends, he identifies the culprit behind his parents' murder 15 years ago, which had been his trauma. He is close friends with Furuya.

A detective in the First Investigation Division. During his academy days, he was a classmate of Rei Furuya, Jinpei Matsuda, Kenji Hagiwara, and Hiromitsu Morofushi. He is called "Class Rep" (Hanchou). He ranked second in grades after Furuya and possesses high physical ability and leadership. He was traumatized by an incident where his father, a former police officer, knelt down to a robber in the past, and during his academy days, he held a strong belief that "justice cannot be carried out unless one is stronger than anyone else."

A motorcycle police squad leader in the Kanagawa Prefectural Police. She is Kenji Hagiwara's older sister. In high school, she was troubled by Matsuda, who loved disassembling machines, when he took apart her smartphone. She has a "big sister" vibe—frank and tomboyish, yet her speech carries a certain dignity. In emergencies, she speaks with calm, powerful words, and she has a deeply affectionate side, especially regarding her brother. She doesn't hide her emotions and says what's on her mind directly.