Mokuku is a member of the rabbit-like Rabitta tribe. This character shares a deep, enduring friendship with Kautz, stemming from their shared past in Kautz's home village before Kautz began working at the armor shop. Mokuku accompanies Kautz when he departs the village, remaining a constant companion throughout Kautz's subsequent experiences.

Physically, Mokuku possesses light brown fur and black eyes. A distinctive symbol on Mokuku's apron serves as a unique identifier within the Rabitta tribe, setting Mokuku apart from other tribe members; this symbol is a consistent visual feature.

Within the narrative, Mokuku functions primarily as Kautz's companion animal. The character appears across multiple story arcs but remains silent, lacking speaking capabilities. Mokuku's role centers on providing a consistent background presence rather than driving plot events or undergoing significant character development. Interactions focus exclusively on non-verbal companionship with Kautz, without independent storylines or transformations.

No additional narrative functions, backstory details, or developmental changes are documented for Mokuku beyond these established parameters across all seasons and related media.