Gamera vs. Guiron

Akio and Tom spot a flying saucer while looking through a telescope, then rush to tell Akio's mother. She dismisses their account as childish nonsense, leaving the boys uncertain but determined. The sighting plants the seed for a remarkable adventure.

The next day, the trio bikes to the field to investigate the saucer. They manage to slip inside the craft, drawn by curiosity. The ship suddenly takes off, leaving Tomoko behind as it blasts toward the stars.

The ship speeds toward space, navigating an asteroid field. Gamera appears and clears a path through the debris, allowing the craft to escape the danger. After guiding them, Gamera lingers as the ship continues toward an unknown planet.

The spacecraft lands on the outskirts of an alien city on Terra. A silver Space Gyaos appears to menace the ship, while a second monster with a blade-shaped head, Guiron, emerges from an underground lair to threaten the boys. The stage is set for Terra's strange, peril-filled salvation.

Guiron and Space Gyaos clash; Space Gyaos fires a beam that Guiron's blade-shaped head deflects, severing Space Gyaos' leg. The duel continues as Guiron breaks off Space Gyaos' wings and, ultimately, decapitates it, ending the alien scout's threat.

Akio and Tom explore the city and meet Barbella and Florbella, Terra's last inhabitants. They learn Terra orbits the sun opposite Earth and has remained undiscovered. The Terrans reveal that Guiron is their final defense against the Space Gyaos.

Barbella and Florbella incapacitate the boys and restrain them, turning to extract knowledge from their minds. They reveal their plan to probe Akio's brain for nourishment and to learn about Gamera and the boys' fondness for children. Akio is shaved as part of the preparation.

Gamera lands on Terra in a rescue attempt. The Terrans unleash Guiron against the giant turtle, hoping to defeat him. Gamera counters with flame and brute force, standing firm against the knife-headed invader.

Gamera grapples Guiron, biting one of Guiron's front legs and throwing him toward a monolith. Guiron's shurikens pierce Gamera's cheeks, prompting Gamera to grab ice-like boulders to heal. The two beasts continue their brutal contest, each dealing painful blows as they fight for the upper hand.

Tom wakes and frees Akio, but their escape frees Guiron from confinement. The knife-headed monster rampages through the Terran city, attacking both Terrans and the ship as chaos erupts. In the chaos, the ship is torn, and Barbella is mortally wounded.

Florbella kills Barbella, revealing the cruel euthanasia policy of their society as she explains that useless members are disposed of. The boys witness the harsh reality of Terra's inhabitants as the situation grows direr.

With renewed resolve, Gamera confronts Guiron in a climactic clash and defeats him by pinning the knife-headed monster and using explosive force. Gamera then welds the damaged Terran ship back together with flame breath and returns to Earth carrying the two boys.

The boys are returned to their mothers on Earth, and they bid farewell to Gamera as he flies off into the sky. The remarkable journey ends with the familiar warmth of home, and a grateful nod to their giant protector.