Age: 54. Height: 178cm. 33 years of experience as a detective. Belongs to the Criminal Investigation Division of the Setagaya Police Station, Metropolitan Police Department. Rank: Assistant Inspector. He is in charge of investigating the current series of suspicious deaths. His years of experience, police intuition, observation skills, and decisiveness are all at their peak. He looks like a blunt, gruff old man at first glance, but he is actually quite talkative and a social butterfly despite his appearance. He is a highly skilled detective who has vowed never to share details of his investigations even with family or friends. His motto is "Work with your feet." He is a smoker and favors Seven Stars. He is bad with computers.

Age: 26. Height: 178cm. 5 years of experience as a detective. Belongs to the Criminal Investigation Division of the Setagaya Police Station, Metropolitan Police Department. Rank: Sergeant. Arizumi's subordinate, providing support for this case. He previously worked as a salaryman at a computer company but knocked on the police's door at age 22. He moved from a neighborhood police box to the Setagaya Station and became a detective. He possesses the drive and powers of observation that Arizumi lacks, constantly supporting him as a capable right-hand man. He is proficient with computers and has the ability to look up investigation materials and various records. He gets along well with Ayame, his partner. He smokes American Spirit.

Age: 27. Height: 168cm. 7 years of experience as a detective. Belongs to the Criminal Investigation Division of the Setagaya Police Station. Rank: Sergeant. She has been a detective since she was 20 and was taught the ropes by Arizumi. Thanks to that, she has inherited his deductive reasoning, observation skills, and drive. Two years ago, she was a victim of stalking, but she repelled the attacker using her skills in karate and judo. After arresting him, she threatened him with a smile, saying, "If you stalk me again, I'll rip your balls off, you idiot," proving herself to be a formidable woman who could intimidate a yakuza. However, she has a weakness for delicious food and often sneakily helps herself to Saito's cup noodles.

Age: 52. Height: 192cm. 31 years of experience as a detective. Belongs to the Criminal Investigation Division of the Setagaya Police Station, Metropolitan Police Department. Rank: Assistant Inspector. A detective who mainly deals with yakuza and thugs. He is harsh toward criminals but treats his colleagues normally. When it comes to a case, his expression changes, and his already intimidating face becomes even more menacing, rivaling that of a mobster. He is strong in matters related to organized crime. He likes sweets and enjoys Japanese and Western confectionery during breaks. He smokes Caster 5mg. He looks up to Arizumi as a senior.

Age: 38. Height: 167cm. 15 years of experience as a detective. Chief of the Criminal Investigation Division at Setagaya Police Station. Rank: Inspector. The direct superior of Arizumi and Shindo. Although her rank is Inspector and she is their superior, she addresses Arizumi and Shindo with honorifics and polite speech. Originally in the Traffic Division, she moved to the Criminal Investigation Division 18 years ago. She solved various cases, becoming a Division Chief and promoted to Inspector at the young age of 38. She is beautiful but frank and has a meticulous personality. She uses both the carrot and the stick, being strict at times and kind at others. She has a husband and a high school-aged child, managing both her work in the field and her household duties.

Age: 58. Height: 175cm. Chief of Setagaya Police Station. Rank: Commissioner. A station chief who rose through the ranks without being on the fast track. In his younger days, he gained various experiences dealing with yakuza and murder cases. Since becoming Chief, he no longer goes out into the field, but he is a rare kind of chief nowadays who gives 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 at the same time, he is a responsible person who wants to fulfill his duty as a police officer. He likes coffee and is often seen brewing his own in the pantry and drinking it in the break room (which isn't particularly strange).