Mukumuku is a large flying squirrel born in the Greenhill Forest, distinguished by his signature red cloak and a full-blooded, hot-blooded sense of justice. He first met the protagonist Riliu, his sister Nanami, and their friend Jowy during their training in Kyaro. Nanami discovered Mukumuku mimicking Riliu’s martial arts moves and pounced on him; she named him Mukumuku for his soft, fluffy fur, and the group accepted him as a close childhood friend. Mukumuku frequently rode the breeze from Greenhill to Kyaro, partly drawn by the appeal of human foods. When Riliu, Nanami, and Jowy were forced to flee Kyaro under false accusations of treason, Mukumuku joined them, initially seeming to want to continue their play. After staying with the party, he eventually reestablished the Flying Squirrel Corps—a team of five similarly named squirrels that includes Makumaku, Mekumeku, Mikumiku, and Mokumoku—and became its leader, responsible for naming its members. In battle, Mukumuku supports his allies with his agility and gliding ability, and his squad can execute a combined Five Squirrel Attack. During the Dunan Unification War, he serves as a loyal companion and a scoutlike presence, often spending time with Nanami when Riliu is away on army duties. After the conflict ends, Mukumuku returns to his native Greenhill Forest. His core motivation is a steadfast sense of justice and deep loyalty to the friends he made in Kyaro, and he approaches situations with an earnest, sometimes exuberant fervor that matches his passionate nature.