During the dusk of one day, the girl maid Yuuki, who may act reckless at times, was secretly protecting her future master who was returning home from school. This future master was summoned to his grandfather’s villa and found himself facing a large robot army and a man with a hideous face. Faced with so many enemies, Yuuki had to reveal her identity as the secret bodyguard. What is the identity of this master who is attacked by sexy maids and giant robots? And why is that? The key is linked to a certain secret closely related to him…