User blog comment:XGlass Reflection/Ch. 54 Review~ Erwin of the Rebellion/@comment-118.136.106.200-20140213075624/@comment-24521263-20140213195656

She is only considered female in the anime. In the manga, the author specifically stated that "she" didn't have a gender.

But yeah it's weird to look at after you've watched the anime, lol.