Some points out that it was an exception that Masayuki HOSHINA served the fourth shogun Ietsuna TOKUGAWA as his koken (the guardian), but this guardianship was unofficial because Masayuki was not appointed to any post of the shogunate.
保科正之の4代将軍徳川家綱の後見は、例外的だとする指摘もあるが、この後見も、何らかの幕府の役職に就任して行われたものではない。