Chibi Kero: Kerobouru no Himitsu!?  

Chibi Kero: Secret of the Kero Ball!?

Once upon a time, there was a young Keroro who wanted to show off his Kero Ball to Pururu. He borrowed it from Giroro's brother Garuru and started playing with its buttons. However, while doing so, he accidentally transported four tadpoles inside the ball. To escape, they had to win a pinball maze. Meanwhile, in the outside world, a young blue tadpole named Kururu picked up the Kero Ball and heard cries for help from within. He struck a deal with the trapped tadpoles to free them if he got a plate of curry rice. The deal was accepted, and with the help of the Kero Ball, a large plate of curry rice was produced for Kururu. Unfortunately, the plate continued to grow bigger and bigger until Kururu was completely immersed in it. As the film came to an end, the yellow curry transformed Kururu into the "yellow devil," and the sound "Kukuku" was heard.