Keisuke Itonokogiri, known in English adaptations as Dick Gumshoe, is a homicide detective who serves as a primary contact for defense attorneys and prosecutors involved in major cases. Aspiring to law enforcement since childhood, he built a working bug detector during his youth that would later prove useful in actual police work. Before joining the force, he worked part-time as a mover. His early career had a rocky start; on his first day as a homicide detective, he mistakenly reported to his old post, leading to a salary cut from a superior. A week later, while guarding a defendant lobby, he shared snacks with a young girl named Kay Faraday. When the prosecutor and defendant in the adjacent room were found dead, Itonokogiri faced wrongful murder accusations himself. Rookie prosecutor Miles Edgeworth cleared his name, forging an unwavering loyalty from the detective that would define much of his career.

In personality, Itonokogiri is optimistic, hardworking, and eager to please, taking great pride in his work and his bond with the prosecutor's office. He is cheerful and well-meaning, though not particularly sharp or observant, often failing to collect all available evidence or making genuine mistakes in his testimony. Despite his professional shortcomings, he is courageous and dependable, willing to risk his job and personal safety to help those he trusts. He is known for addressing others with the informal term pal, reflecting his friendly and unpretentious nature. He can be easily discouraged by harsh comments but remains fundamentally resilient. His financial struggles are a recurring aspect of his life; due to frequent pay cuts from prosecutors frustrated with his errors, he often lives on instant noodles.

His primary motivation stems from a deep-seated loyalty to Miles Edgeworth, whom he credits with saving his career and reputation. He consistently goes out of his way to support Edgeworth, even when it means disobeying orders or putting his own job at risk. He also holds a genuine desire to see justice served and takes his responsibilities seriously, though his enthusiasm sometimes exceeds his capability. His dedication to his work is balanced by a childlike enthusiasm that makes him easily approachable, especially to children.

Within the story, Itonokogiri typically handles initial crime scene investigations and is usually the first witness called to the stand during trials, providing basic facts about the case and presenting evidence gathered by the police. He frequently works alongside defense attorney Phoenix Wright, often providing crucial assistance or information that helps solve cases. While ostensibly aligned with the prosecution, he often helps both sides, creating internal conflict as he wants to support justice above all else. He appears in numerous cases throughout the series, sometimes risking his job to provide access to restricted files or evidence.

His key relationships are central to his character. His bond with Miles Edgeworth is the most significant; despite Edgeworth cutting his pay and threatening to fire him, Itonokogiri remains fiercely loyal and protective. With Phoenix Wright, he maintains a friendly but occasionally rivalrous relationship, often helping the defense attorney despite technically working for the prosecution. He harbors a romantic crush on former police officer Maggey Byrde, though he never directly admits his feelings. He easily befriends children such as Pearl Fey and Kay Faraday, showing a gentle and playful side. He also endures the strict and often violent supervision of prosecutor Franziska von Karma, who frequently uses a whip on him.

In terms of development, Itonokogiri grows from a bumbling rookie detective into a more seasoned investigator, though he never becomes exceptionally sharp. His competence fluctuates across different cases, but he consistently rises to critical moments, providing essential support when it matters most. He experiences several temporary dismissals from the police force but is typically reinstated, often after his contributions prove vital to solving major cases. His loyalty and courage become more pronounced as the series progresses, establishing him as a reliable, if unconventional, ally.

Regarding notable abilities, Itonokogiri demonstrates surprising technical aptitude. He is skilled at building and maintaining investigative gadgets, having constructed a functional bug detector as a child and later creating the Blue Badger, a moving police mascot used in a critical investigation. Despite his absent-mindedness, he possesses physical courage and has faced down dangerous individuals to protect others. His persistence and dedication often compensate for his lack of natural investigative talent, allowing him to uncover or safeguard key evidence through sheer determination.