Decades into the future, humanity is under siege by an alien race known as the Novas. These inhuman beings leave devastation in their wake whenever they appear, with the efforts to stave them off becoming known as Nova Clashes. Young women known as "Pandoras" and young men known as "Limiters" are implanted with stigmata to give them superhuman powers and are trained in military academies, where they must learn to work together if humanity is to have a chance of surviving.