Hajime Morioka serves as the Division 1 Section Chief within the police force and is a supporting character in the story. As a high-ranking officer, his background is defined by his extensive experience and a results-driven approach to police work that stands in stark contrast to bureaucratic or political considerations. He is Aiji Yanagi’s former boss, and it is established that everything Yanagi knows about being a police officer he learned directly from Morioka, highlighting Morioka’s role as a crucial mentor and foundational influence on one of the key protagonists.

In terms of personality, Morioka is a fiery and intense individual. He possesses a keen intuition and a sharp mind, but his most defining trait is his deep disdain for prioritizing appearances and internal politics over tangible results. This pragmatic and straightforward attitude defines his leadership style and his approach to law enforcement. His primary motivation lies in effectively overseeing investigations and getting results, particularly in the face of crises, rather than maintaining a polished public image or adhering strictly to procedural formalities for their own sake.

Within the narrative, his chief role is overseeing the X-Day Investigation, a major case that drives the plot forward. As Section Chief, he holds a position of authority and is responsible for directing resources and managing the overall response to the shadow organization's campaign of violence in Shinjuku. The most critical relationship in his background is his mentorship of Aiji Yanagi. This connection is significant because it links him directly to the core group of characters working to solve the case, placing him as a figure of authority and respect from the protagonist's past. Information regarding his other key relationships, personal development throughout the story, or notable abilities beyond his intuition and investigative experience is not available.