On the top secret Moekko Island, a man named Kanzaki Takahiro unconditionally trains combat maids for their duties. When an older inefficient model named Rinia is brought to the island, however, Takahiro can't voice his disapproval more, but takes her in under company orders. From washing windows to cooking, to keeping the company's clean-up squad from invading, there's never a dull moment in the lives of Takahiro, Rei (the company's representative) and bumbling Rinia, gothic Kazusa, and the rest of the combat maids of Moekko Island!
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!