Chibi-Kuru represents Kururu's younger, childhood form on Keron before his yellow coloration and distorted personality emerged. Appearing as a blue Keronian tadpole without his signature glasses and headphones, he displays more typical behavior than his future self. His key involvement occurs during an incident with the prototype Kero Ball device.

Discovering the tadpole forms of Keroro, Giroro, Zeroro, and Pururu trapped within the Kero Ball, Chibi-Kuru hears their pleas. He intervenes by pressing buttons on the device, accidentally freeing them. As payment for his help, he demands a lifetime supply of curry. The Kero Ball produces an enormous plate of curry rice that rapidly expands out of control, completely submerging Chibi-Kuru.

This immersion in the yellow curry permanently dyes his skin from blue to yellow. Simultaneously, the event triggers a profound personality shift, marking the emergence of his characteristic dark traits. The incident concludes with him adopting his iconic unnerving laugh, "Kukuku," signaling his transformation into the cynical and eccentric Kururu. The curry exposure is the direct source of both his yellow pigmentation and the development of his antagonistic persona, including his social detachment and sadism.