Sempai and kohai what do they mean?
A simple translation is sempai means senior, someone who has gone before you, who started training before you. It has nothing to do with grade. So why do we use Sempai? I can,t really remember when it started but someone must have thought, what title do I give a shodan or a nidan. That is how sempai started, when I trained in Japan I would know who my sempais were but I did not address them as sempai. And kohai means junior not by age but those who started training after you. So you can have a shodan who is a kohai to a lower grade simply because he started training after him or her.
