A young Keroro attempts to impress Pururu by showing off the Kero Ball, a ball that Giroro borrowed from his brother Garuru. While pressing the buttons to test it, Keroro accidentally transports the four tadpoles inside the ball. To escape, they must win the pinball maze. In the outside world, a young blue tadpole named Kururu picks up the ball and hears cries for help. He makes a deal: he will free those trapped inside if he receives a plate of curry rice. A deal is a deal, and with the Kero Ball, a plate of curry rice appears for Kururu. However, the plate grows bigger and bigger and bigger, becoming so large that Kururu is submerged in the curry. The yellow curry slowly transforms the blue Kururu into the "yellow devil," and just as the film is about to fade to black, a "Kukuku" is heard.
