However, it was not easy to attain this goal from the beginning because some systems, such as Oni no sei (the automatic promotion of people at the age of 21, whose parents were from Imperial Prince down to the fifth rank, or whose grandparents were higher than the third rank), were set up to give priority to the descendants of men of high rank to get promotion easily.
しかし、高位者の子孫には一定以上の位階に叙位する制度（蔭位の制）を設けるなど、当初からその目的は達成困難なものであった。