Originally, government posts were directly connected with national jobs and it was Ikai that showed their social status; but because the posts started to symbolize their social and family status, the fundamental rules of Kanisoto (Kani matching), which had existed since the beginning of the Ritsuryo system (the system of centralized administration established under the Ritsuryo codes), started to change.
本来、官職はその国家的仕事に直結し、自己の身分を示すのは位階であったが、官職が身分や家柄を示すようになったため、官位相当という令制以来の原則にも変化が現れ始めた。