Kuchiba is a supporting character in Children of the Whales. He resides on the Mud Whale and is one of the Unmarked, meaning he does not possess the psychic power known as thymia and therefore enjoys a normal, unshortened lifespan. He serves as an aide to the island’s mayor, assisting with administrative duties and the enforcement of community rules. His personality is defined by strictness and a straightforward manner. He is easily annoyed and reacts with extreme, often exaggerated irritation to any breach of protocol, such as becoming visibly upset when Chakuro cries during a funeral. This over-the-top frustration can make him appear somewhat immature despite his position.

Kuchiba’s primary motivation is to maintain order and uphold the traditions of the Mud Whale, reflecting a deep investment in the stability of their isolated society. His role in the story is that of a minor official who provides procedural support to the mayor and occasional comic relief through his dramatic outbursts at rule-breaking. In terms of relationships, he frequently clashes with the young archivist Chakuro, whose emotional nature and occasional disregard for custom draw Kuchiba’s ire, and he works closely with the mayor and other council members as a loyal subordinate.

Kuchiba undergoes little personal development throughout the narrative, remaining consistent in his rigid, rule-bound demeanor. As an Unmarked, he possesses no combat or supernatural abilities; his influence comes solely from his administrative position and his forceful, authoritative temperament.