Bunzō Aoki operates as a Tokyo Metropolitan Police detective investigating the central narrative's dismemberment cases and disappearances. He tracks the mysterious gloved man, Shunkō Kubo, to an abandoned temple hideout. Though Kubo escapes their confrontation, Aoki persists in his investigation. Later, he participates in the police raid at Dr. Kōshirō Mimasaka's research hospital alongside central figures including Akihiko Chūzenji and lawyer Noriyuki Masuoka. During this operation, amid the chaotic climax of Mimasaka's attempted escape and death, Aoki attempts to arrest the doctor for unethical surgical experiments involving Kubo's limb severance. His professional duties involve coordination with law enforcement colleagues such as Detective Shutarō Kiba.