While helping out at Jono Zoo, twin brothers and animal lovers Raiga Kudou and Kuga Kudou hear voices calling to them. Following the voices, the two rush to Earth headquarters, where their father, Dr. Bariki Kudou works. This was a fact they were not aware of. There, they encounter vehicles called Core Granners, which the voices tell them to get inside. Raiga and Kuga do so, and are instructed on what to do by the staff of Earth Granner...