The Izu Peninsula Is in Danger!. A mysterious volcanic island emerges from the Sea of ​​Japan causing tsunamis and eruptions that cause dozens of deaths and injuries in the city. The same night a Demon Robot, accompanied by a fleet of enemy jets, attacks Saotomè's laboratory and the boys are preparing to leave. Unfortunately the enemy bombs have set fire to the launch pads: the take-off is very dangerous but the heroes manage to pass and hook up to give life to the Getta Robot. The white weapon fight begins between the heroes and the enemy monster but after a short fight the captain of the demons is called back to base by Hidler, allowing the Getta team to take a breath. Subsequently it is decided to investigate the mysterious island and Getta Poseidon dives to the ocean floor but an electronic network traps the robot and the enemy takes the opportunity to bomb the laboratory. Ryo, Hayato and Musashi, landed with diving suits, go out into the open sea to eliminate the net and, after a hand-to-hand combat with demon-sub soldiers, find their way back to the surface. Thanks to Rygar's speed, the heroes return to base in the blink of an eye, just in time to wipe out the enemy fleet and battle the demon robot. This time it is Ryo's turn who engages in a tough battle with the tough monster who does not decide to die but thanks to an impeccable strategy he gets rid of the demon, foiling its threat once again. Eventually Mikiru also comes into play and, with a giant bomb, nuclearizes the new volcanic island, causing it to sink into the ocean where it came from.