In the not-too-distant future, mankind has taken its initial steps toward exploring the outer reaches of the cosmos. They uncover a massive race of insectoid aliens known as "Space Monsters," who appear to be devoted to the annihilation of humanity as they get closer and closer to discovering Earth. As a result, humanity creates massive battle robots operated by hand-picked teenagers from throughout the planet. Shortly after the aliens are discovered, Noriko Takaya, the daughter of a famous deceased space captain, enrolls in a training school despite her dubious abilities as a pilot. There, she meets her polar opposite, the gorgeous and gifted Kazumi Amano, and is suddenly forced to collaborate with her in order to overcome the trauma of war.