Lucifer is a fallen angel and one of the Devil King's generals. After the Devil King was transported to human world, he and Olba became allies in order to defeat the Devil King so he can return to heaven. After being defeated by the Devil King however, he moves into the same place as Sadao and Shirō. He's good with technology and loves playing video games.
He was an angel, though he fell because it was too "boring".
He lives together with Maou and Ashiya in their small apartment after he was defeated and is trying to find out how to find enough power to bring them home using the internet.