In the hidden war against the Saint, mankind has been saved countless times by an android named Mahoro. After her latest battle, Mahoro discovers that if she stays in her full battle mode, she has a limited time of life left to her. If her armaments are removed, Mahoro has a new lease on life and the freedom to live them as she pleases, at least for 398 days. So what`s an android with a little over a year left to do? Enter Suguru, a young orphan, who hires Mahoro on as a maid. Poor Suguru has no idea about Mahoro`s past life, or her deep connection to him. But he`s not one to complain as Mahoro moves in causing suspicion from his friends, and jealousy from his home-room teacher. Now Suguru just has to decide if his beautiful 19-year old maid is really an android!