This change was brought about by MINAMOTO no Yoritomo who opened up the bakufu to acquire the right to establish Mandokoro, which until then had only been open to court nobles ranked Jusanmi (Junior Third Rank) or higher.
これは幕府を開いた源頼朝が上記のものと同じく従三位以上の公卿に許される政所開設の権利を獲得した