Choujuushin Gravion (Light Novel)

In the distant future, the universe is under attack by robotic destroyers named Zeravire whose goal is to eradicate all of mankind. Enter Klein Sandman, a millionaire with a penchant for saving the world – or at least, one can assume. He’s built the mecha Gravion, a machine capable of destroying the Zeravire with the help of several young pilots, but piloting it comes at a high price. Along with sheltered Toga, well endowed Mizuki and a varied cast of pilots and maids alike, young Shigure Eiji must help lead Gravion to victory, else all of humanity will perish!