Kaoru Jōjima, also called Joji, was a police superintendent who partnered professionally with Soumei, later known as the "Black Fang." In his youth, Jōjima closely resembled his grandson, Kuniharu Ogino. His hair, originally black, turned grey with age. Soumei characterized Jōjima as frequently raising his voice. Jōjima held steadfast trust in the police force and the Secret Dobermen unit. Although personally uncorrupt, discovering systemic police corruption caused him significant internal conflict. Realizing the overwhelming difficulty of maintaining truthfulness amid pervasive deception, he shot himself in the head approximately 30 years before the series' main events, coinciding with his grandson Kuniharu's birth. His suicide followed a critical conversation with Soumei, where Soumei revealed the Secret Dobermen's refusal to cooperate due to police corruption. Unable to reconcile this, Jōjima ended his life. Authorities suppressed his suicide note, declared it nonexistent, blamed Soumei entirely for the incident, and imprisoned Soumei. On the same full moon night as Jōjima’s death, Soumei escaped his physical body, beginning his existence as an entity inhabiting other bodies. Soumei later sought his "son," Hiroshi Inaba's, help to relocate his original body for survival. Jōjima’s family included a deceased wife and daughter, and a son-in-law. His direct descendants are grandson Kuniharu Ogino and great-granddaughter Azusa Ogino. His legacy is defined by his integrity within a corrupt system and the tragic consequences of his inability to reconcile truth with institutional falsehood.