A species from Shinkansen Henkei Robo Shinkalion that lived on Earth's surface in ancient times, but was forced underground after the meteor that destroyed the dinosaurs collided with the planet. There are very few of them alive at the point of the series, and they send kaijuu to the surface to attack humanity.
They look similar to humans, although they have red or yellow eyes, pale skin, and either very light blonde or grey hair. Some of them have been shown to be able to take on forms indistinguishable from humans, although Genbu and Torame are notable for looking much more monstrous and inhuman compared to the others. They can also take upon kaijuu forms themselves when infused with the black particles they use to create kaijuu on the surface.
The movie reveals that the underground Kitoralsus are not the only group, and that other groups, descended from Kitoralsus that left the planet after the meteor strike, are still present in space and waiting for a chance to return to earth