The story tells the story of the second-year high school student Manatsu Daji witnessing an incredible circular rainbow light over Tanegashima on TV the night before the summer vacation. The earth that had seen this kind of rainbow light was surging inside, and decided to head towards Tanegashima alone. Complex thoughts such as "the mystery of the father's death in an accident" and "the memory of the incredible girl I met in childhood" gush out from his chest. The land that reached Tanegashima met the "EarthEngine" due to the alarm sound of a certain facility. "Are you the captain..." Along with the voice of inquiry, what the earth saw was the mysterious complete mechanical life form "KILL-T-GANG" from Uranus, and the boy's adventure also began in this gorgeous starry sky.