User blog comment:IamJakuhoRaikoben/Chapter 249: Magic is Alive, Review./@comment-80.181.135.20-20110904231439/@comment-16344653-20110905031444

Since there probably is a reason why Mashima hasn't told us their last name, I think it would be Guran Doma since he is the chairman of the council (like someone I know) and is the only one other than Yajima with a last name