Chibi Kero: Kerobouru no Himitsu!?

Synopsis

A youthful Keroro attempts to win Pururu's admiration with the Kero Ball, a borrowed item. An accidental activation traps him and his companions within the ball's pinball maze, where victory is their only escape. Meanwhile, a young Kururu discovers the ball and agrees to free the captives in exchange for curry rice. However, the meal escalates in size, engulfing Kururu and transforming him into a "yellow devil" as a sinister laugh echoes.