Gokamon refers to a family with distinguished family lineage. It is also called as kamon.
In the Edo period, among all the sinpan (relatives of the Tokugawa family), it specifically referred to a family of the Tokugawa shogunate, and daimyo (a feudal lord) families and hatamoto (a direct retainer of the shogun) families with a family line of brothers of Ieyasu TOKUGAWA (founder of the Tokugawa shogunate, and the first shogun of the Edo bakufu, Japanese feudal government headed by a shogun). The gokamon families were allowed to use the surname of Matsudaira, Iyeyasu's former surname. Most of the gokamon including the Echizen Matsudaira family, head of gokamon, did not take up posts of the bakufu (Japanese feudal government headed by a shogun) but were highly respected for their social status as the shogun family.
The Echizen Matsudaira family – offspring of Hideyasu YUKI, Ieyasu's second son.
The Aizu Matsudaira family – offspring of Masayuki HOSHINA, an illegitimate son of Hidetada TOKUGAWA, the second shogun
The Ochi Matsudaira family – offspring of Kiyotake MATSUDAIRA, a younger brother of Ienobu TOKUGAWA, the sixth shogun.
In addition, some clans with a strong matrimonial relation with the shogun family such as the Maeda clan of the Kaga Domain, the Ikeda clan of the Tottori Domain and the Ikeda clan of the Okayama Domain were treated correspondingly to the gokamon and granted the surname of Matsudaira and the family crest of Mitsuba aoi (three leaves of Hollyhock, which is a family crest of the Tokugawa family).
However, Tokugawa gosanke (three privileged branches of the Tokugawa family: the Kishu family, the Mito family, and the Owari family) and gosankyo (three privileged branches of the Tokugawa family: the Tayasu family, the Hitotsubashi family and the Shimizu family) used the surname of Tokugawa and received exceptional treatment.