One day while Shirou is delivering a secret device to his colleague, he meets Amane Mao, a super-strong girl capable of lifting cars. This device, the VITA system, is a new weapon theoretically capable of defeating ERRORs: a breed of enormous, cybernetic mutants that necessitated the use of weapons of mass destruction on Old Tokyo fourteen years ago. Suddenly, one such ERROR appears before the two and goes on a rampage. Shortly after a failed argument to convince his colleague to approve use of the VITA system simply to save civilians, his colleague is devoured by the ERROR. Faced with death, Shirou has no choice but to accede to Mao's request to activate the super-weapon and destroy the ERROR. ...and thus Shirou's eventful days as the male master of the VITA system at St. Liddel's Girls' Academy are about to begin... (Source: Edited from AnimeSigma)

The year is 2070. Hajime, a curious and outgoing second-year class rep at Misumaru Middle School, leads what he thinks is a quiet and ordinary life in the town of Tenmo. But, one day, two events turn all of his conceptions about the world around him upside down: the appearance of a giant white mecha fighting off an apparent alien invasion, and the arrival of Muryou Subaru, a transfer student with a predilection for old-fashioned (for the time) school dress and remarkable talents for combat and use of telekinetic power. As Hajime soon discovers, Muryou isn't the only person at Misumaru with special powers and responsibilities, either. How is it all connected to the alien Galactic Federation and the strange white giant called Shingu?