Chibi-Robo is cleaning the exterior of a space station when his companion Telly reminds him to take a break. During the break, Chibi-Robo watches television and discovers that a lot of the natural resources on Earth have vanished, disappearing because of invading aliens. The pair are suddenly disturbed by a cluster of aliens, known as the Gyorians, who are making their way towards Earth. As such, they both set out in the "Chibi House" to combat the alien invasion.[2]: 12 During the adventure, Chibi-Robo travels to all continents of the world to reclaim the stolen resources and defeat the alien robots that guard their specific continent.[16]
The two eventually head to Antarctica where the Aliens' Mothership is located. Chibi-Robo promptly destroys the Mothership, but an orb escapes the wreckage and heads towards a metropolitan city in Asia. The orb then transforms into a large monster named "The Mega-Mech Menace" and starts to wreak havoc. To combat the monster, Telly and Chibi construct a giant named "Giga Chibi-Robo"; the two giants battle each other until Chibi-Robo deactivates the monster and destroys it, prompting both Chibi and Telly to head back to the station