Hailing from the Momotarō folktale as one of the peach boy's companions alongside Kakisuke the monkey and Rurio the pheasant, Shiro now serves within Japanese Hell's Animal Cruelty division. In this role, he punishes deceased humans guilty of animal abuse during their lifetimes.

Physically, Shiro appears as a white-furred canine with grey eyes, typically adorned by a red-and-white yorishiro rope around his neck. His personality starkly contrasts between professional duties and personal interactions: during torture assignments, he displays ferocious intensity befitting his role, while outside work he radiates consistent cheerfulness, energy, and friendliness. This amiable nature fuels his frequent companionship with Hozuki, whom he accompanies during activities and administrative tasks throughout Hell.

Within Animal Cruelty Hell’s hierarchy, Shiro reports to superiors Yasha-ichi and Cookie. His folktale origins occasionally resurface through Kakisuke’s lingering remorse over past actions toward crab families during their shared adventures. A four-panel spin-off manga, "Shiro no Ashiato" (Shiro's Footprints), focuses on his character.