It's quite common for people to think that attaining the rank of blackbelt signals the completion of your training. This is simply not true. In fact, it's just like attaining any other rank in karate. Certain new doors will be open to you for training. Whether it's learning a new kata, being considered ready to engage in a different type of training, or anything else, attaining a new rank opens doors. Lots of doors open when you become a blackbelt.