The Jaryuu Clan is a race of Reptilian humanoids, the result of genetic manipulation of Dinosaur DNA. But their true origins are tied to the ancient civilization of Lemuria, which is said to be the very first civilization to exist in an unknown ancient continent and mastered genetic research. They are bent on reverting the earth to the age of the dinosaurs, exterminating all of humanity, and ruling the world with the power that the "Precious" provide, because they believe that, with their dinosaur genes, they are the true heirs of Earth. However, according to Souta, they are not very smart. A Jaryuu can go for eternity without water. Their name translates into "Evil Dragon".
Jaakuryuu are the human-sized monsters that were created the ritual fight each other to the death, only one survivor remains. Once King Ryuuwon awards him by transforming the surviving Jaryuu into a strongest Jaakuryuu. Ryuuwon invented special dart from his gun to enlarged Jaakuryuu.
Daijayruu are the Jaryuu Clan's giant monsters and cybernetic, genetically altered reptilians which must be piloted from within. They have the kind of steering wheel that one would find in a nautical ship and the cockpit of most Great Evil Dragons is also a throne room for King Ryuuwon.