Kageyama, whose full name is Yoshiaki Kageyama, is a veteran law enforcement officer working in a futuristic version of Tokyo. His professional background is that of a former police detective who has since become a narcotics investigator, operating under the authority of the Ministry of Health Department. Within this department, he leads a team dedicated to stopping illegal drug activity, with his subordinate Yasumoto assisting him in his pursuit of criminals.

In terms of personality, Kageyama is portrayed as a dogged and persistent agent, determined to capture his targets and bring them to justice. His methods are noted to be somewhat old-fashioned, relying on analog techniques that stand in stark contrast to the highly advanced, AI-driven digital society he operates within. This makes him something of an anachronism in his own world, but it also speaks to his experience and unyielding nature. His primary motivation stems from his role as an agent of the law, as he is committed to dismantling the drug trafficking and crime that lurk beneath the surface of Tokyo’s seemingly perfect automated utopia.

Within the story, Kageyama initially serves as an antagonist figure, a narcotics agent who is on the trail of the protagonist, Kai, and her involvement with a group of rebel motorcycle couriers known as Suma Garage. He is a persistent threat, dedicated to capturing the group and holding them accountable for their unregulated activities. However, his role in the narrative evolves as the true criminal conspiracy is uncovered. He forms a key alliance with the Suma Garage group, as they are both being manipulated by a higher-level official within the city's digital ministry. This leads to an uneasy but necessary cooperation where they join forces to expose the real antagonist. His most significant relationship is therefore with the Suma Garage, transitioning from a determined pursuer to a reluctant ally in uncovering the truth.

A key aspect of Kageyama’s development is this shift in perspective. While he begins firmly on the side of the established order, the revelation that a trusted official is orchestrating the crimes he is investigating forces him to re-evaluate his position. His commitment to justice ultimately outweighs his adherence to the system, leading him to work alongside the outlaws he was hunting. As a former detective and current head of the narcotics division, Kageyama possesses considerable investigative skills and experience. His notable ability lies in his persistence and his deep understanding of criminal procedure, even if his methods are not the most technologically advanced. He is a capable leader and a formidable adversary, whose primary strengths are his knowledge, his experience, and his unwavering sense of duty.