Keroro, aiming to impress Pururu, showcases the Kero Ball loaned by Giroro from his brother Garuru. Accidentally activating the buttons, he transports four tadpoles inside the ball, leading to a pinball maze challenge for their escape. In a twist, a blue tadpole named Kururu finds the ball in the outside world, striking a deal to release the trapped tadpoles in exchange for a plate of curry rice. As the deal unfolds, the curry rice mysteriously grows uncontrollably, engulfing Kururu and triggering a transformation into the menacing 'yellow devil.' The tale concludes on a mysterious note as the screen fades to black, accompanied by the ominous laughter of 'Kukuku.'