A ship runs aground on a mysterious atoll leading to an investigation by insurance representative Kusanagi, who discovers an ancient bead that he gives to his daughter Asagi. Meanwhile, ornithologist Nagamine investigates reports of a new species of large bird named Gyaos. As the Gyaos begin to attack, an ancient guardian with a bond to Asagi emerges.

After already conquering hundreds of planets, the Great Star League Gozma sets its sights onto Earth. To defend the lands in such a great crisis, the military begins a special branch known as the Earth Defense Force, comprised of elite members from all areas of the military. Under the supervision of Commander Ibuki, the numerous gathered soldiers of the Earth Defense Force begin a harsh training.