The term miyake
("palace household") refers to twelve families formed by non-heir
members of the Japan
ese imperial family
. Until the Allied occupation of Japan
were considered to be part of the imperial family: now, they're all commoners.
The oldest and most influential of the miyake is the Fushimi family, which dates back to the 1400's. Fushimi Kunie, who lived in the 1700's, is a common ancestor of four other miyake families. The Katsura, Arisugawa, and Kanin families were created during the Edo era, and the Meiji era reforms led to the formation of even more miyake families: Nashimoto, Kuni, Yamashina, Kitashirakawa, Kaya, Asaka, Higashikuni, and Takeda.
During World War II, many members of the miyake were commissioned as high officers in the Japanese military. Asaka Yasuhiko, who many believe was the mastermind behind the Rape of Nanking, was one of them. None of them were ever convicted as war criminals, however: the Allied Occupation of Japan merely purged them from public life, so many set up successful businesses after the war and lived quite comfortably.
Eight of the miyake still exist today. Fushimi Hiroaki is an executive with Mobil, and Takeda Tsunetada leads a team at Mitsubishi. Kaya Harunori has served as ambassador to Brazil, Denmark, and Israel. They aren't royalty anymore, but they've still got power.