1957

In the real worl

 * Godzilla, King of the Monsters! (the American edit of Gojira) is released in Japan.
 * The Mysterians is released on December 28 in Japan.

In the DaiKaiju universe
An alien race known as the Mysterians attack the Earth with the robot monster Moguera and take the women of Earth, but are soon defeated. (The Mysterians)