The Book Theif Monster

Something or someone is eating my books. Every time I look into my school bag, another book is missing. So far I'm missing my spanish notebook, my vocab book, a novel from home, and a novel from the library. I've checked my house and my locker and my classrooms. I've also checked my car. Where else could they be? I've come to the conclusion that there is a book theif monster in my backpack eating my books.