Gamera vs. Guiron

While scanning the skies through their telescope, two young boys, Akio and Tom, spy a spaceship descending into a nearby field. They tell Akio's mother what they have seen, but she dismisses their story as childish nonsense. The next day, the two boys — with Akio's younger sister, Tomoko, went to the site to investigate.
Akio and Tom managed to steal into the spaceship. But then, without warning, the ship takes off, leaving Tomoko behind and soaring into outer space toward a field of asteroids. The two boys panic, but united Gamera appears and clears a path for the ship through the asteroids.
The spaceship leaves Gamera behind, flying near the speed of light, and transports the boys to an unknown planet. Akio and Tom explore a portion of the alien city and meet the planet's only inhabitants: two beautiful women named Barbella and Florbella, who explain that their planet, known as "Terra," orbits the sun directly opposite the Earth, which is why it has never been discovered by earth's astronomers.
Suddenly, they turn on Tom and Akio and put them into restraints. Using their super-technological devices, the alien women probe the boys' minds. In the process of learning about Gamera's weakness, it's up to Gamera to stop Guiron and take the two boys back to Earth.