Every time you complete a dojo, you'll go up in belt rank. Once you've gotten your brown belt, you're allowed to challenge the Master Dojo in order to get your black belt and take it over . You may challenge the dojos in any order.

These are the belt ranks:

White (default), Yellow (one dojo completed), Orange (two dojos completed), Green (three dojos completed), Blue (four dojos completed), Red (five dojos completed), Brown (six dojos completed), Black (all dojos completed, master defeated).