The Galactic Federation is concerned about the number of wars on the Planet Earth. It sends three agents to determine if the planet is a potential threat to the universe, and whether it should be destroyed. The instrument of destruction is a device resembling a large black ball with two antennae that is variously called an anti-proton bomb, a solar bomb, and a neutron bomb. The agents (Captain Bokko, Nokko, and Pukko) are originally humanoid in appearance, but upon arrival on Earth they take on the appearances of a rabbit (Bokko), a horse (Nokko), and a duck (Pukko) that they had captured as examples of Earth life forms. While on Earth they travel in a tire-shaped vehicle capable of enormous speeds called the Big Wheel, which can travel on both land and water (and, with modifications, through the air)
as Bokko or Bonnie in the American version
as Nokko (Ronnie in the American version)
as Kōichi Hoshi (Randy Carter in the American version)
as Pukko (Zero in the American version)
as Shinichi Hoshi (Kenny Carter in the American version)
