In the Garden Where the Hydrangeas Bloom
Suguru Misato, a young teen boy living by himself since his parents have passed away a few years ago, decides to hire a maid to help clean up his house. Enter Mahoro, a former combat android created to defend the Earth against a secret alien invasion in the early 1980's. Given the choice of continuing in her service for Vesper and functioning for a mere 37 days or retiring, giving up her combat armor and continuing to function for 398 days, Mahoro has chosen to serve as a maid to one Suguru Misato.
Aired 06/10/2001EP 1 - In the Garden Where the Hydrangeas Bloom
Mahoromatic: Automatic Maiden
Vesper is a secret agency fighting an army of alien invaders by using super-powerful battle androids. Mahoro is Vesper's most powerful battle android and has won many battles, but she has little operating time left and soon will cease to function. However, if she lays down her arms and conserves her remaining power, the time she has left can be prolonged to just over a year. Mahoro is given an opportunity to live the remaining time she has as a normal human. She chooses to live as a maid for Suguru, a phenomenally messy high school student who lives by himself after his family passed away.
(Source: Anime News Network)