Ukon is a century-old Bunraku puppet, meticulously crafted during the early Meiji era by a renowned puppet maker. His physical form features jointed fingers enabling intricate manipulation and traditional Japanese attire: hakama, tabi socks, geta clogs, and a distinctive yuigesa collar historically linked to mountain monks, hinting at unorthodox spiritual traits. Visually, his red hair contrasts sharply with puppeteer Sakon's black hair, symbolizing their opposing personalities.

Operated by Sakon, Ukon exhibits a personality radically different from his reserved puppeteer: loud, talkative, flirtatious, rude, egocentric, and prone to jumping to conclusions during criminal investigations. He frequently becomes irritated when Sakon withholds deductions or suspicions. This dynamic creates a "Double Consciousness," where Ukon voices thoughts Sakon cannot express directly, functioning as two aspects of one psyche. Their interactions resemble a sibling-like bond, with Ukon often inspiring confidence in Sakon and crime victims.

Ukon's primary role involves assisting Sakon in solving murder mysteries across Japan. He participates in eight major cases, including investigations at an abandoned school, a puppet mansion, an Egyptian museum, and a Noh theater family. During these cases, Ukon demonstrates a unique spiritual ability: channeling the souls of the deceased. This allows murder victims to temporarily possess Ukon's body, enabling them to convey final words or critical information about their deaths. This power, combined with Sakon's ventriloquism, facilitates confrontations with culprits and often forces confessions. Ukon's aggressive, outspoken demeanor contrasts with Sakon's quietness during interrogations, creating a psychological advantage.

Ukon shares a combative rapport with Sakon's aunt Kaoruko, a police detective, often teasing or provoking her. His dependence on Sakon is evident when Ukon suffers damage in a workshop fire, leaving Sakon temporarily unable to perform investigations effectively, underscoring their symbiotic relationship. Across story arcs, Ukon evolves from a mere investigative tool into a crucial emotional conduit for Sakon, particularly during high-stakes situations like a family puppeteer event where Sakon faces mortal danger. The puppet’s presence remains constant through all cases, culminating in appearances by previous allies during Sakon’s pivotal performance.