Mukumuku is a large Flying Squirrel who comes from the Greenhill Forest. His trademark is his red cloak, as well as his full-blooded sense of justice. He sometimes rode the breeze as far as Kyaro Town in the Highland Kingdom. Part of his like of humans was because of their delicious foods.
In the past, while the hero and Nanami were training in Kyaro, Nanami found the squirrel imitating his moves. She sneaked behind the flying squirrel and leaped upon him. Bringing him back to the hero and Jowy, she named the squirrel Mukumuku after his soft fur and the group have known him ever since. As such, he was something of a childhood friend.
When the hero, Nanami and Jowy were forced to flee from Kyaro under accusation of treason, Mukumuku joined them in their escape, perhaps intending to play with them as he did in the past. Staying with the party, he would eventually reform the Flying Squirrel Corps with four similar flying squirrels. As captain, he was responsible for naming the other members of the squad.
Before entering your home in Kyaro Town, examine the tree behind the house three times and Mukumuku will join you. If you miss this opportunity, Mukumuku can be recruited randomly in Greenhill Principality by walking between Greenhill City and the Muse-Greenhill Checkpoint with an empty slot in the party.