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.

It's summertime and a everyone travels to the beach for some fun in the sun! However, things go awry when an alien anti-android robot appears and strips off all the female bathing suits *ahem*. Mahoro must now return briefly to her combat mode to take care of this threat. Will she be able to take care of this now that she has discarded her combat armor?