Roppu was a toy abandoned by the child of aliens. He was rediscovered by Roppei, the son of a fisherman. Roppu can fly when the button on his chest on is pressed. Roppu can also create anything, even things thought to be impossible. When the star on his head is pressed, Roppu falls still. Roppu and Roppei have all sorts of adventures, with questionable figures often trying to get their hands on Roppu for their own desires.

Volume 2 includes "Bongo" (First Grader version): Bongo is a boy who lives in the jungle and is a master archer entrusted with maintaining peace in the jungle. Bongo learns of a treasure called the Golden Bow, and goes in search of it along with his ally Chap the Squirrel. The two must overcome seven perils to reach it at the Mountain of the Sinking Moon.