theres this boy, Katzuki, who starts having visions of giant robots fighting. Everyone thinks he's weird, except the most popular girl in school, Mitsuki Sanada. She takes him to her dad who works on science things about a parallel dimension. Somehow Kazuki and Mitsuki are transported to the other dimension and work for Mitsuki's parallel dad. They fight in a war of a few ppl against a few other ppl. They pilot the big robots and so on. It eventually leads to the parallel worlds combining (which will destroy them both) and trying to stop that from happening.