Akari Niimura, a member of the National Defense Force, transforms into Geyser Phoenix to battle the Insaidar aliens who seek Earth's resources. One day, she is ordered by her commanding officer to guard an excavation site of an ancient robot and heads to the location. Suddenly, a mysterious man appears, escorted by Insaidar soldiers. This man is Orga, an ancient robot that had been disguised as a human! Orga throws himself into danger to protect Akari, and the two gradually grow closer. However, they are pursued and cornered by both the National Defense Force and the Insaidar. Then, a shocking truth is revealed—Orga was originally created as a weapon to exterminate Earth's intelligent life and destroy the Sacred Beast God: Great Geyser! After regaining his memories, Orga mercilessly attacks, leading to a devastating assault on Geyser Phoenix... [BAD END]