Mahoro was employed as a maid by Suguru Misato who was the junior high school student who was living alone, and she came to his house. Because she took care of him heartily every day, there was no break in his tension. Additionally, the classmate and teacher Shikijo are involved, too, and there is no end of troubles in their daily life. Moreover, Mahoro was the strongest android in Vesper which was the organization to oppose the invasion of the space alien to the earth. However, the longevity of Mahoro who had fought as a field type android hardly remained.