Age: 54. Height: 178cm. 33 years on the force. A detective with the Setagaya Police Station, Criminal Investigation Division. Rank: Assistant Inspector. He is in charge of the current serial suspicious death investigation. His years of experience have honed his intuition, observation, and initiative to their peak. Though he looks like a blunt, gruff old man, he is actually quite talkative—a master communicator and a sharp detective. He makes it a rule never to discuss investigations with family or friends. His motto is "work the beat with your own two feet." He is a smoker who favors Seven Stars. He is terrible with computers.

Age: 26. Height: 178cm. 5 years on the force. A detective with the Setagaya Police Station, Criminal Investigation Division. Rank: Sergeant. Arizumi's subordinate, providing support for this case. He previously worked at a computer company before joining the police at 22. After starting at a neighborhood police box, he was transferred to Setagaya and became a detective. He possesses the initiative and keen eye that Arizumi lacks, serving as a highly capable right-hand man. He is proficient with computers and skilled at digging through digital records and investigation materials. He gets along well with his partner, Ayame. He smokes American Spirit.

Age: 27. Height: 168cm. 7 years on the force. A detective with the Setagaya Police Station, Criminal Investigation Division. Rank: Sergeant. She has been a detective since she was 20 and was taught the ropes by Arizumi. Thanks to that, she inherited his deductive reasoning, observation skills, and drive. Two years ago, she was targeted by a stalker but fought them off using her mastery of karate and judo. After the arrest, she gave the culprit a smile and a threat that would make a mobster blush: "If you ever stalk me again, I'll rip your balls off, you moron." Despite her tough nature, she has a weakness for good food and often sneaks bites of Saito's cup noodles.

Age: 52. Height: 192cm. 31 years on the force. A detective with the Setagaya Police Station, Criminal Investigation Division. Rank: Assistant Inspector. A detective who primarily deals with yakuza and thugs. He is harsh toward criminals but treats his colleagues normally. When it comes to a case, his expression shifts, making his already intimidating face look even more terrifying than a gangster's. He is an expert in organized crime cases. He loves sweets and enjoys Japanese and Western confections during breaks. He smokes Caster 5mg. He looks up to Arizumi as a senior mentor.

Age: 38. Height: 167cm. 15 years on the force. Chief of the Setagaya Police Station Criminal Investigation Division. Rank: Inspector. The direct supervisor of Arizumi and Shindo. Although she outranks them, she addresses them with honorifics and polite speech. Originally in the Traffic Division, she transferred to Criminal Investigation 18 years ago. After solving numerous cases, she rose to Chief and the rank of Inspector at the young age of 38. She is a beauty but has a no-nonsense, meticulous personality. She balances strictness with kindness, masterfully using the carrot-and-stick approach. A mother of a high schooler, she balances her duties in the field with her responsibilities at home.

Age: 58. Height: 175cm. Chief of the Setagaya Police Station. Rank: Senior Superintendent. A chief who rose through the ranks without the fast-track "career" exam. In his younger days, he gained extensive experience in organized crime and homicide cases. Now that he is Chief, he rarely goes into the field, but he is a rare type of leader who offers advice to young detectives and officers. His hobbies are running and bonsai. Since his second grandchild was born, he secretly wants to retire early, but his sense of duty as a police officer keeps him focused. He loves coffee and is often seen brewing his own in the kitchenette to drink in the breakroom (which isn't really that strange).