Gamera, the Giant Monster (1965)

Dr. Hidaka, accompanied by his assistant Kyoko Yamamoto and photographer Aoyagi, travels to an Eskimo settlement in the Arctic aboard the vessel Chidori Maru to look into the myth of an unusual species of turtle mentioned in their folklore. As Dr. Hidaka confers with the Eskimo chief, several unidentified stealth aircraft fly over the area. The captain of the Chidori Maru contacts a nearby American military base, which scrambles several fighter jets to intercept the unidentified aircraft. When the aircraft do not respond to the American fighters' warnings and open fire on them, the American planes fire their missiles and successfully shoot down one of the stealth aircraft. The aircraft crashes onto an icy plain several miles away from the Eskimo village and explodes. Watching the explosion from afar, Hidaka and his crew realize that the aircraft must have been carrying nuclear weapons, as a mushroom cloud becomes visible over the Arctic. Though Hidaka and the village are a safe distance from the nuclear detonation, the explosion cracks open the Arctic ice and a gigantic bipedal turtle emerges from the crevice. The creature roars ferociously and makes its way to the Chidori Maru, smashing it with its colossal arms and killing all aboard. As Hidaka and his crew prepare to leave, the Eskimo chief presents him with a stone carving, which depicts a giant turtle among what appear to be waves. Hidaka asks the chief if this is the legendary giant turtle that lived on the lost continent of Atlantis, and the chief replies that it is indeed the "Devil's Envoy," Gamera.

Following the sinking of the Chidori Maru, Hidaka travels to New York City to answer questions from the press regarding Gamera. Hidaka says that Gamera was in very close proximity to the nuclear explosion that freed him from his icy prison, so he will eventually perish from the lethal dose of radiation he absorbed. Hidaka remarks that it is a shame, as Gamera would have been a valuable scientific specimen. Meanwhile, flying saucers are being sighted all across the globe, especially in Japan. While returning to Japan aboard a plane, Hidaka, Aoyagi and Kyoko remark that since Gamera is likely lying dead on the sea floor, flying saucers have become the new craze. In a small village in Hokkaido, Nobuyo Sakurai is informed by a schoolteacher that her little brother, Toshio, has been a disruption in school because he has been bringing turtles to class. Nobuyo promises that she will talk to Toshio about it, and at dinner that night she and her father tell Toshio that he must let his pet turtle, Chibi, return to the wild. Toshio reluctantly takes Chibi out near the ocean and places him in a small shelter built from rocks, promising that he will be back to see him tomorrow. As Toshio turns to go back home, he sees Gamera appear over the cliffside. He runs to his sister to warn her, and they look up to see Gamera begin climbing ashore. Toshio runs into the lighthouse in the village, but Gamera swings his arm and breaks the lighthouse in half, leaving Toshio hanging for his life from a rail. As Toshio loses his grip and falls, Gamera catches him in his hand and gently sets him down on the ground before returning to the sea.

After learning that Gamera is still alive and in Hokkaido, Hidaka, Kyoko and Aoyagi travel there to consult with Professor Murase and the JSDF to discuss countermeasures. When Gamera lands at a power plant, Murase determines that Gamera possesses a sort of internal furnace that allows him to feed on inorganic materials like coal, petroleum, fire, and nuclear material, then convert them into organic substances and use them for sustenance. Hidaka tells the JSDF to hold off on firing at Gamera, and use the high-tension wires around the plant to repel him. To their surprise, Gamera tears through the wires and seems to draw power from them. Hidaka tells the JSDF to open fire on Gamera with their artillery, but it has no effect either. Murase concludes that Gamera's body tissues are so dense that they are stronger than even the strongest metal alloys, so he is completely immune to conventional weaponry. With Gamera rampaging across Hokkaido, the JSDF is left with no option but to contact the American military and ask for a nuclear strike against Gamera. However, Hidaka is informed of an experimental cadmium freezing bomb developed by the JSDF, and decides that it may be effective against Gamera. Hidaka tells the JSDF to cancel the nuclear strike, as Gamera withstood a nuclear explosion at point-blank range and only grew stronger, and instead lure Gamera to a hilltop and drop the freezing bombs on him. Once Gamera reaches the summit of a hill, several freezing bombs are dropped onto Gamera, covering him in ice and rendering him immobile. As the freezing bombs are only effective for ten minutes, JSDF soldiers scramble quickly to plant dynamite on the hill while Gamera is frozen, then detonate it, sending Gamera tumbling down the hill and causing him to land on his back. The JSDF celebrates, believing Gamera will be helpless on his back and eventually die of starvation. To everyone's shock, Gamera retracts his head and limbs into his shell, then begins to spew flames from the openings. Gamera floats up from the ground and begins spinning rapidly, then flies off into the distance. Hidaka realizes that the Eskimo carving does not show Gamera among waves, but rather clouds, and that the "flying saucer" sightings were actually sightings of Gamera while he was flying.

Gamera is sighted around the world, but thankfully has not attacked a major populated area. When bizarre shipwrecks and flooding begin occurring around the Tokyo Bay area, Hidaka determines that Gamera is sleeping under the bay, and will inevitably come ashore. Hidaka meets with representatives from both the United States and the Soviet Union, and together they form one last countermeasure against Gamera: Z-Plan. As Z-Plan is prepared at Izu Oshima, Gamera comes ashore that night and ravages Tokyo. To keep Gamera occupied until Z-Plan is completed, trains filled with petroleum are sent towards Gamera so he can feed on them. Toshio, having moved to live with his uncle in Tokyo while his home in Hokkaido is repaired, climbs aboard one of these trains so he can get a closer look at Gamera. Since Chibi was nowhere to be found after he returned to visit him, Toshio believes Chibi turned into Gamera, and that Gamera is his friend. A worker sees Toshio on the train and pulls him off of it just as it crashes, then tells him to go home. Nobuyo is preparing to evacuate the city, but cannot find Toshio, who stows away on a ship bound for Izu Oshima. On Oshima, Hidaka and the JSDF make the final preparations for Z-Plan. A trail of petroleum is laid from Tokyo all the way to the island, then is ignited at nightfall. Gamera sees the flames and follows them to the island, but a typhoon hits the island and extinguishes the flames. Aoyagi, having sneaked onto the island posing as a laborer, sets the tents on the island ablaze to keep drawing Gamera there. Gamera sees the fire and begins to come ashore, but the typhoon increases in intensity and blows the flames out. Fortunately, Mount Mihara briefly erupts, and the eruption draws Gamera further inland. With Gamera successfully lured to Izu Oshima, Z-Plan can finally be enacted.

The following morning, Nobuyo comes to the island and is reunited with Toshio, who wants to observe Z-Plan as it is put into motion. Using fuel from an underground silo, flames are shot from holes in the ground near the center of the island. Gamera is drawn into the middle of these towers of flame, and becomes trapped when the ground opens up and a huge capsule closes around him. The capsule is actually attached to a rocket ship, which launches from the island and exits the atmosphere, bound for Mars. While Gamera could not be vanquished on Earth, the world is now safe from his terror as he is banished to the barren plains of Mars. When asked if he is sad that Gamera is gone, Toshio replies that he is not, and vows he will travel to Mars and visit him someday. Toshio waves as the Z-Plan rocket enters outer space, and wishes Gamera goodbye.