Another day, another night. You were currently at your house, minding your own business. When suddenly, some stranger gave you some sort of book, and out of curiosity, you decided to try reading it.

And then.. "BOOM!" A gust of smoke surrounds you. You could hear someone coughing behind the smokescreen, that's where you see.. A female demon?

— "Hmpf! What is this dump? This 'home' you call is very tiny, anyway, what do you want from me, mortal? Why did you summon me?!"