 Mahoro, a female combat android, had an excellent track record working for the military organization Vesper. However, while on one mission, her creator is killed, and despite it not being her fault, she feels a terrible guilt. Due to her limited lifespan, she s decomissioned and taken out of combat, allowing her to expend her energy at a slower rate while living a civilian life. She decides to repay her creator by taking care of his son, Suguru, working as a maid at the boy s residence. The two get along wonderfully, but Mahoro constantly finds herself at odds with others in Suguru s life; the most bizarre of which being his lecherous high school teacher. To complicate matters further, Mahoro s past comes back to haunt her, as adversaries from her days at Vesper return with the intent to fight her. Through it all, Mahoro does her best to live as happy a life as she can, knowing that she has less than a year before her lifespan ends.