Age: 54. Height: 178cm. Detective experience: 33 years. Belongs to the Detective Division of the Metropolitan Police Department's Setagaya Station. Rank: Assistant Inspector. He is in charge of investigating the current series of suspicious deaths. He has mastered every aspect of the job, including years of experience, police intuition, observation skills, and decisiveness. While he looks like a blunt old man at first glance, he is actually quite talkative and a master of communication. He has a strict rule never to discuss investigations with family or friends. His motto is "Work with your feet." He is a smoker and favors Seven Stars. He is poor with computers.

Age: 26. Height: 178cm. Detective experience: 5 years. Belongs to the Detective Division of Setagaya Station. Rank: Sergeant. Arizumi's subordinate, providing support for this case. He previously worked at a computer company but joined the police force at age 22. After starting at a neighborhood police box, he was transferred to Setagaya Station and became a detective. He possesses the drive and powers of observation that Arizumi lacks, serving as a highly capable right-hand man. He is proficient with computers and has the ability to look up investigation materials and various records. He is on good terms with Ayame, his partner. He smokes American Spirits.

Age: 27. Height: 168cm. Detective experience: 7 years. Belongs to the Detective Division of Setagaya Station. Rank: Sergeant. She has been a detective since age 20 and was taught the ropes by Arizumi. Thanks to that, she has inherited his reasoning, observation, and action skills. Two years ago, she was targeted by a stalker but fought him off using her karate and judo skills. After his arrest, she famously threatened him with a smile, saying, "If you stalk me again, I'll rip your balls off, you moron," proving she is a powerhouse detective who can out-intimidate a mobster. However, she has a weakness for good food and often sneaks Saito's cup noodles.

Age: 52. Height: 192cm. Detective experience: 31 years. Belongs to the Detective Division of Setagaya Station. Rank: Assistant Inspector. A detective who primarily deals with yakuza and thugs. He is harsh toward criminals but treats his colleagues normally. His expression changes when a case begins, turning his already intimidating face into something even more terrifying than the mobsters he hunts. He is an expert in matters related to organized crime. He loves sweets and enjoys Japanese and Western confectionery during breaks. He is a smoker, favoring Caster 5mg. He looks up to Arizumi as a senior mentor.

Age: 38. Height: 167cm. Detective experience: 15 years. Chief of the Detective Division at Setagaya Station. Rank: Inspector. The direct superior of Arizumi and Shindo. Although she holds the rank of Inspector and is their superior, she addresses Arizumi and Shindo with honorifics and polite speech. Originally in the Traffic Division, she transferred to the Detective Division 18 years ago. She solved various cases and rose to the position of Division Chief and the rank of Inspector at the young age of 38. She is beautiful but has a no-nonsense, meticulous personality. She is a master of the carrot-and-stick approach, being strict at times and kind at others. She has a husband and a high school-aged child, balancing her work in the field with her household responsibilities.

Age: 58. Height: 175cm. Chief of Setagaya Station. Rank: Commissioner. A station chief who rose through the ranks without the elite "career track." In his youth, he gained extensive experience with yakuza and murder cases. Since becoming Chief, he no longer goes into the field, but he is a rare type of Chief who offers advice to young detectives and officers. His hobbies are running and bonsai. Since the birth of his second grandchild, he secretly wishes to retire early, but he is also a man of great responsibility who wants to fulfill his duty as a police officer. He loves coffee and is often seen brewing his own in the kitchenette and drinking it in the break room (which isn't really that strange).