Resume : After seeing a strange full-circle rainbow appeared near Tanegashima Space Center on TV news program with strange deja-vu feelings, high school sophomore Daichi Manatsu traveled to Tanegashima (where his father serving as the commander of the Space Center) on the first day of his summer vacation. There he met a mysterious girl Hana Mutou, a genius hacker Akari Yomatsuri, a quiet boy Teppei Arashi (but with fiery side), and — to his biggest surprise — a giant robot called "Earth Engine," designed to repel invading KILL-T-GANG, a mysterious mechanical life form from Uranus. Meanwhile, the invasion from KILL-T-GANG is already underway, giving Daichi and his team of teenagers no choice but to pilot Earth Engine to defend his home planet.