User blog comment:IamJakuhoRaikoben/Chapter 403: Erza vs. Kyouka, Review./@comment-1776824-20141006205617/@comment-85.221.190.231-20141007095541

Actually, you are all wrong. I did the research :P and it seems that pain receptors and touch receptors are two different things, look here: []

So it seems it's perfectly plausible that Kyouka can turn off touch receptors while leaving nociceptors active. Also, feelings from inside the body (proprioception) are different sense than touch, so Erza could technically feel inner pain.

Still, I don't think we should be made to roam through PubMed to understand manga :D