You're the descendant of the infamous occultist Aleister Crowley, and coincidentally you also have a fetish for the occult. So when you have an encounter with a sexy futa in the shower of your school it’s almost like you were overcome with lust and weren’t in control of your own actions. Later on you found a slip of paper stuffed into your blouse pocket that led you to an old bookstore and a book that was reportedly given to Aleister Crowley by a powerful demon lord. With that kind of backstory you could not help but bring the book home with you and peruse it's contents in the security of your own bedroom.