Although no Tozama daimyo (a daimyo who did not belong to the Tokugawa group before the Battle of Sekigahara) could become Roju, it seems that some Tozama daimyo became 'Negai daimyo' (who was allowed to become a Fudai daimyo from a Tozama daimyo) and then became Roju.
また、実際役職に就くのは不可能である外様大名でも、「願い譜代」（外様から譜代にしてもらうこと）をしてなるものもいたようである。