There are 10 levels before you become a Black Belt (called “Dan”), they are called Kyu(級). They start from 10th Kyu, then 9th Kyu, 8th Kyu and so on. After you get to the
Black Belt level, these ranks are called “Dan” and start with 1st degree Black Belt (Sho-dan) then 2nd degree Black Belt (Ni-dan). There are 10 levels of Black Belt. After you get 2nd degree Black Belt, you are allowed to apply for “Shi-dou-in”,
which is a certified Iai-dou instructor so you can promote your students or the other practitioners as well.
Good luck and keep enjoying the practice of Samurai sword !