A mysterious phenomenon occurs in a hot spring in Beppu. It foreshadows the appearance of the legendary giant monster Bugon, a guardian deity who has been watching over Oita since ancient times. The locals band together to stop the rampaging Bugon, who releases hot spring water from his mouth, but...
An attack takes place on Rainbow Bridge in Odaiba, Tokyo by the fighter helicopter `Gray Ghost`. 2 days earlier, the Gray Ghost was stolen. The perpetrators are followers of Yukihito Tsuge. Yukihito Tsuge planned a coup of Tokyo 13 years earlier. The leader of Special Vehicle Section 2, Keiji Gotoda, sets out to stop the terrorists.
