Atlantis is a lost civilization that was said to have sank into the depths of the ocean. It only appears in the manga version of Getter Robo G.
Atlantis was once a thriving civilization with technology that surpassed the present day. One day a meteor fell from the sky and introduced a space disease that was quickly overwhelming the population. To save themselves, the Atlanteans created Uzahra to store themselves in order to wake up in a different era.
Waking up in the present day, they are confronted by the Getter Robo G who fights against Uzahra in spite of its overwhelming advantage. Impressed, the Atlanteans attempt to take the bodies of its pilots in order for their brains to inhabit them and take over the planet. However, before the procedure could begin, the Getter Team were ready to damage themselves and Hyakki Empire enforcers attacked Uzahra, wiping out the sleeping inhabitants until they are dealt with by the Getter Team. The remaining Atlanteans give the Getter Team Uzahra to defeat the Hyakki Empire.
Atlantis possessed great technology that even surpassed that of the Getter Robo, Dinosaur Empire and Hyakki Empire; able to have an entire robot safely use cryogenic stasis for extended periods of time, and negate gravity. Many theories about its disappearance were common throughout history including the possibility that Uzahra destroyed it. Atlantis itself wanted control over Earth thinking its society was perfect but later gave its technology in order to save it from the Hyakki Empire who wiped out its remaining population.