This image speaks for itself. This was taken from the official translation of Volume 9 by Kodansha USA, and while I don't really care for Nanaba's gender, I'm actually dreading the huge shitstorm that this will cause.
I know we have decided to leave Nanaba as female, as it was decided based upon what the Anime production team decided, but now we have mister Sheldon Drzka slipping some "Mister Nanaba" in-between to add to the debate.
So, what will we do in regards to this? Because as for name spellings, we had already decided that Kodansha USA's word was law. But as for character genders?