Hamura is a young detective working in the First Section of the Criminal Investigation Division. He is characterized by his energetic and passionate approach to his work, initially displaying a strong, almost singular focus on capturing the perpetrators of the terrorist attacks known as Sphinx. This eagerness is tempered by a more conventional and dismissive mindset regarding the culprits, as he is reluctant to give them credit for their elaborate schemes and views them merely as disrespectful children, a perspective rooted in ageism.

His primary role in the story is as a foil and junior partner to the veteran detective Kenjirou Shibazaki. At the outset, Hamura is distrustful of Shibazaki, disapproving of what he perceives as Shibazaki’s academic interest in the mysteries and riddles posed by the terrorists rather than a direct pursuit of the suspects. This creates a significant point of conflict between them, with Hamura wanting to act on traditional police work and follow leads immediately, while Shibazaki is more willing to step back and attempt to understand the terrorists’ psychology. Hamura's frustration stems from being outmaneuvered by individuals he considers his juniors, which bruises his professional pride and makes him eager to prove that the police force is still in control.

Despite his initial resistance, Hamura's attitude undergoes a gradual change as the investigation progresses. He becomes less stubborn and begins to develop a grudging respect for Shibazaki's unorthodox methods. This development culminates in a key moment where he demonstrates his own investigative value, providing Shibazaki with a crucial piece of information about a person taking photographs with a balloon, which proves to be a significant clue in solving the case. This shift indicates his growth from a hot-headed, dismissive officer into a more effective and open-minded detective who can contribute meaningfully to complex problems.

Hamura does not possess any extraordinary abilities, but his notable skills lie in standard police detective work. He is shown to be competent in following evidence and analyzing surveillance footage, even if his initial conclusions are often incorrect. His most significant contribution is his persistent legwork and attention to detail, which ultimately yields the vital lead that helps advance the stalled investigation. Through his relationship with Shibazaki, his arc illustrates the journey from conventional, pride-driven policing to a more thoughtful and collaborative approach.