Moku the Bear Cub is a supporting character introduced early in the narrative. Discovered moaning in distress from an injured foot, he is aided by Iwaki, father of Anju and Zushio, establishing his connection to the human family.

Moku consistently appears with his mouse companion, Chonko. Both animals possess the ability to communicate freely with humans, unlike more conventional animals such as the family dog Ranmaru. This anthropomorphic trait allows them direct participation in events.

Their primary role involves providing comic relief and moral support to Anju and Zushio during hardships. Moku and Chonko actively rally other forest animals to confront the antagonist Onikura, causing him and his attendant to tumble into a river. This intervention demonstrates their loyalty and opposition to injustice through indirect action.

Moku and Chonko serve a tonal purpose; their comedic vignettes are juxtaposed against the film's tragic elements, like the family's enslavement, creating narrative tension between human suffering and fantastical animal interludes.

Moku's physical design reflects the animation style of earlier works from the same studio, bearing visual similarities to the bears in "Hakujaden" and the character Son Goku from "Saiyuki," suggesting specialized animators were utilized.

Beyond confronting Onikura, Moku and Chonko are later depicted returning to the family estate while pursued. Both subsequently fall victim to drugging by slave traders, mirroring the fate of Anju, Zushio, and their mother, temporarily removing them from the narrative during the protagonists' captivity.

Their presence contributes to the film's thematic exploration of passive resistance. Alongside other forest creatures, they actively resolve challenges faced by the human characters through indirect actions.