Gigantic Mechanical Brain Gillvalis and the Galactron Army, intent on wiping out all intelligent lifeforms in the universe, close in on Earth. Riku Asakura heads for Okinawa, where there are said to be clues to the "Red Steel" sought by Gillvalis. There, Riku encounters Ail, who realizes that he is Ultraman and assigns him an important mission. Meanwhile, the Galactron Army begins attacking Okinawa in search of the "Red Steel". Ultraman Geed, Orb, and Zero rush to Earth, but Geed's hasty actions in sticking to his mission put the Ultraman team in even more danger! - Gigantic Mechanical Brain Gillvalis and the Galactron Army.