The Sandersons bought a Giga-Robo for unknown reasons, and liked him very much. One day, when an alien ship was about to crash in the Sandersons' backyard, Giga-Robo caught it, preventing the crash. As thanks, the Aliens decided to give Giga-Robo two wishes. Giga-Robo's first wish was to "give soul to toys", a wish that brought them all to life. After realizing that the energy consumption of Giga-Robos was way too high and nearly bankrupting the Sandersons, Giga-Robo's second wish was for Giga-Robos around the world to have a body that wouldn't require energy, but, because the aliens were out of wishes, they had to go get more. In the absence of the aliens, Giga-Robo would eventually be deactivated and left to collect dust in the basement.
Many years later, when Chibi-Robo came, the aliens returned to grant Giga-Robo his second wish. After Chibi-Robo successfully reactivated Giga-Robo, he made his wish. Giga-Robo now lives peacefully with the Sandersons, Chibi-Robo, and all the toys that thank him for bringing them to life.