My question is he attending a wizarding school, how come he already has wizarding garb? If he has stolen the book from wizards what was his profession before and what would he be wearing then. My first thought from the title and the image without reading the description is "Oh it is a boy studying magic at an institution" not "Oh he is a rogue wizard learning on his own." as for the collar I think it is alright for the anime kind of style you are going for, it fits the genre but it flows into the clothing a little strange and I do agree a lot with Tinybird that if he is on the run maybe he wouldn't wear such obvious clothing. I would say throw up some style ideas, some rough action poses to gives us a feel for the comic in general. Let us see the enviorment he is in. Obviously it is in a fanstasy world so we may both be wrong and this is the general clothing of everyone.
Hope this Helps!
A Cartoonist is just a lazy Animator.