Puku is a child monster, and is the older brother of Pino.
During the events of Gurumin, Puku is "kidnapped" by the Phantoms in the Potato Ruins, and Parin must save him. At the end of the level, Parin finds Puku trapped in a cage, but he then slips out of it with ease, to Parin's annoyance.
Puku is very helpful to Parin throughout most of the game, until near the end when he reveals himself as the Dark Prince. He then battles Parin with Giga, but is defeated.
Though bested in battle, Puku manages to unseal the dragon Tokaron. After the curse on Tokaron is lifted Puku reveals his background to Parin. Originally he and Pino lived in the forest, however their home was destroyed during the construction of the mine. The pair were found by Motaro and helped to establish Monster Village. But Puku still blamed humanity for ruining their home. Having found the armlet of the Phantom Prince, he set out to trick the escapees of the Phantom Kingdom to help in his plan for revenge.
With his plans failed, Puku asks Parin to finish him off. Instead she and the Phantoms both forgive him, and everyone decides to help rebuild Monster Village together.Puku was last seen before Parin entered the "doorway" leading back home.
Puku has almost the same height than his sister. He has green leaves for hair, eyes containing no irises, a shawl-like light brownish clothing with a yellow lace tied around where his neck is, and brown shoes briefly showing.