The five regent houses (五摂家; go-seike or go-sekke) is a collective term for five families of the Fujiwara clan. The leaders of these families monopolized the position of Sekkan in the Japanese Imperial Court of Kyoto between the 12th and 19th century. The five houses are Konoe, Takatsukasa, Kujō, Ichijō, and Nijō.
The Fujiwara clan also had other families, but traditionally only these five were eligible for regentship. They were the most politically powerful families among the kuge (court officials).
As the imperial clan claimed descent from the goddess Amaterasu, in the Fujiwara tradition the clan descended from another ancient kami, Ame-no-Koyane. Apparently, only these two clans were left in the modern era to claim kami descent.
Partly based on that kami descent, tradition required that emperors may marry only from the Fujiwara and the imperial family itself - the view was that an empress must descend from gods, too. Thus, with the exception of Tokugawa Masako, wife of the Emperor Mizunoo, all Empresses of that long period were of the clans that formed the Sekke or from branches of the imperial family itself.