As both the Godzilla Squard, and Robert in the Red Ronin speed after Godzilla, the King of Monsters is suddenly transported to the moon. There it fights a creature known as the Beta-Beast, which Godzilla eventually destroys with its powerful fire breath.
Following the creatures defeat, Godzilla is confronted by the beings who transported him to the moon: aliens of the Betan race. These aliens appeal to Godzilla, telling the monster that their world has been at war against the Megans for centuries using giant monsters as weapons against each other. With the war effort depleting the Megan supplies, they have sent three of their monsters: Triax, Rhiahn and Krollar to Earth in order to plunder it.
With Godzilla accepting the mission, he is transported back to Earth just as the Red Ronin is confronted by the first of the invaders: Triax.