Chibi Kero: Kerobouru no Himitsu!?

A young Keroro attempts to impress Pururu by showcasing the Kero Ball, a ball borrowed by Giroro from his brother Garuru. While testing the buttons, Keroro accidentally transports the four tadpoles inside the ball. To escape, they must navigate a pinball maze. In the outside world, a young blue tadpole Kururu discovers the ball and hears the cries for help. He strikes a deal to free those trapped inside in exchange for a plate of curry rice. The deal is honored, and a plate of curry rice is produced for Kururu. However, the plate grows larger and larger, eventually immersing Kururu in the curry, transforming him into the "yellow devil" as the film fades to black with a sinister "Kukuku" echoing.