It's a Summer that will change the course of history! After witnessing a rainbow that Daichi recalls only seeing once in his childhood, he returns to his hometown hoping to unravel the mysteries from his memories. But his well-meaning investigation has led Daichi to become a defender of the Earth as a part of the secret organization called Globe. Armed with a gun artifact called Livlaster', a massive mecha powered by an Earth Engine', Daichi must fight an alien race to protect his home. Can he beat this group known as the Planetary Gear's and will he and his friends all make it out alive?