This is for ranking up, you start as 1st Dan, your next rank is 2nd Dan, this should come reasonably fast in ranked matches, you’ll see a Promotion Chance come up before the match starts, so long as you win this match, you get promoted into the next rank 2nd Dan, if you lose, you’ll just have to try again. If the other player happens to quit out, the win is yours and you will be ranked up in these cases as well.