I'm a middle school teacher. Sure, ban it from school librarys. I get it. Attack on Titan is.... not really meant for children. I have no idea how far the show has gotten as far as the manga, but i think the show was pretty tame in comparison.

That being said, we also ban weed and guns and even cell phones in school. But google a middle schooler smoming in the bathroom and the video was taken on a students phone. So sure, tell them its not age appropriate, but dont expect it to do anything.