Sixteen years after a meteor destroyed it, Graviton City has been reconstructed into a futuristic metropolis. Yet, this matters little to Eiko Magami, a superpowered high school student whose sole concerns are her best friend, Shiiko Kotobuki, and arriving at school punctually. Unfortunately, the exceptionally intelligent Biko Daitokuji intends to befriend Shiiko, aiming to replace Eiko as Shiiko's best friend by any means necessary. Biko decides that achieving this requires defeating Eiko in combat. To overcome Eiko's super strength and speed, Biko constructs a mecha and challenges her at their school gate. As the two begin their battle, an enormous spaceship hovers over Earth, searching for something left behind.