In the dojo community, advanced students of aikido are called Yudansha (black belts), the beginners are called Mudansha (unranked and kyu ranks).You will not become a Yudansha only by improving your ability. It is also necessary to strengthen your mind and soul according to the way of the warrior. A Yudansha always gives more to the dojo than he takes. For him, the dojo is more than a sports center. It is a part of his life and the members are a part of his family.
Therefore, in the dojo, all the members are connected in a Sempai (Senior) and Kohei (junior) relationship. Everybody, even the teacher, is always a sempai and kohei at the same time. The sempai is the senior member despite his physical skills or the degree he might have. The kohei is the junior member. Even if he is more skilled and higher ranked than his senior, the kohei has to respect him as long as he lives. The senior takes care of his junior and always tries to be a guide to him on his way of budo.