Due to a chance encounter with an actual space pilot. Nono, finds herself becoming part of the elite Fraternity. Made up of teenage pilots called Topless, and armed with quasi-humanoid weapons called Buster Machines, the Fraternity’s mission is to protect the people of the Solar System from attack by swarms of space monsters.

The story revolves around Taiga, who doesn’t have memories from further back than two years ago when his parents died in an accident. He lives with his sister, Tsubame, whom he finds out is from outer space with the job of protecting him as he possesses the Origin Heart.

In a far and distant future, men and women have become mortal enemies. Each living on seperate planets, an interstellar war is being fought between the two very different peoples. Hibiki, a mere 3rd class worker, finds himself in the middle of a huge space battle, facing the nemesis of mankind: Womankind!