User blog comment:Monkey.D.Me/BATMAN Vs. SUPERMAN in ManGotham/@comment-3075024-20130814043422/@comment-3987368-20130814185004

I can agree with that, personally. Mashima is a lot of "style over substance" so a nickname like "Superman" works for him while Oda is a far more careful planner and researcher so "Batman" would fit him.