Sempai and Kohai

The word sempai has a very specific usage in Japanese and it is commonly misused in aikido circles outside Japan. The clearest instances are in a company or university club where the ranking is based on seniority: that is, the specific year of entry. Thus, the founding members of Hiroshima University Aikido Club are called sho-dai (first generation) and successive intakes are numbered in sequence. Hence the first year students now are 35-dai. They are therefore kohai to all who have entered before them and sempai to all who enter after them. Thus Kanetsuk Sensei is the kohai of Fujita Sensei in Takudai. In this specific instance of a university club, the system operates regardless of rank. If there is no clear system of entry into the club, the term has little validity and is not at all based on rank.

先輩 SEMPAI. This is a compound word composed of:

(a) 先 saki, mazu. This is the same character as in the SEN in Sensei, (b) 輩 tomogara, yakara. This word has the basic sense of a member of a group in whatever age, relationship, or status. There are many compounds with different nuances, all depending on the meaning of the first character. The Chinese-derived reading (bei = HAI) with SEN, gives SEN-PAI, a member of the same group but one who joined the group beforehand and is therefore senior.

後輩 KOHAI. This is a compound word composed of: 後 nochi, ushiro, ato, oku(reru). A word with a similar range of meanings as 先, but opposed, e.g., 'after', 'behind', 'subsequent', 'late', and: 輩 tomogara, yakara. This is the same word as in SEN-PAI, above. The Chinese-derived reading (from ho bet) is KO-HAI and means a member of the same group, but one who joined the group afterwards and who is therefore junior.