Keroro, Giroro, Zeroro, and Pururu are Keronian tadpoles who spend their time playing in a secret base. One day, Giroro brings a Kero Ball, borrowed from his older brother Garuru. Young Keroro, ignoring warnings, snatches the ball and presses a mysterious button, creating a vortex that pulls the four friends inside the Kero Ball. Now trapped, the tadpoles must navigate various obstacles within their dark prison.
