I made a rig to my model using Rigify, while most things turned out great, I encountered one problem with my model when it posed, The head starts deforming when rotated. Also, the hair particle doesn’t attach itself with the head either, It doesn’t happen with the arms,only the head part.
From here :
Probably just weight paint it to the head bone. I believe it should be easy as it looks all to be a vale of 1/ red color. Just paint it and watch it go to where it should. I believe.