Dengeki!! Aegis5

is a Japanese light novel series written by Nagaru Tanigawa, with illustrations by Nao Goto. The series began publication on November 10, 2004 by ASCII Media Works under their Dengeki Bunko publishing imprint.

Synopsis
I visited my grandfather's house after being ordered by my parents to monitor my grandfather, who is known as a weirdo scientist. However, there is no grandfather, and for some reason he will live with the five beautiful girls who lived there, and this world is being invaded by something called an invader of another dimension. The erotic artificial intelligence that manages my grandfather's house toward me who is struggling with such a situation laments, "For the past few days, if I do not look into the bath, I will not fall asleep." What should I do?