Eh, the Black Belt. I mean, if it were just the Thief (disregarding his running skills, as the average person won't try low level games) and not a Ninja, then Black Belt would win, but if it were both higher level classes, then the Master would win, so...>_>.
I am amazed that neither of the following occured in this post:
1: Mention of Red Mages
2: Mention of White Mage Kitties