Long ago, in the time of the dinosaurs, the Earth was invaded by an alien menace called Deboth, the leader of an invasion army. On the verge of extinction, some of the dinosaurs are transformed into Zyudenryu and seal Deboth and his forces in ice. Now, in the modern world, the Deboth Army have thawed and now intend to commence the mass extinction of humanity while thawing their still frozen leader. But having prepared for it, Wise God Torin gathers the only people capable of helping the Zyudenryu stop the Deboth Army: "the People of the Great and Mighty Lizards", which has been shortened to "Kyoryugers"