In the original storyline as aired in Japan, Dairugger XV was simply an exploration robot, as well as an intended peace-keeping force. The Earth is in a time of prosperity. The president of the Terran League (the "Galaxy Alliance" in Voltron) launches a mission to explore beyond the galaxy. After commencing its mission of exploration, the starship Rugger-Guard is attacked by a ship of the Galbeston Empire. Dairugger, the super robot, is deployed in order to defend the Earth. It is somewhat by fate that they must help the people of Galbeston find a new planet before it explodes, and…
Source: MAL