Emperor Seiwa
The is a Japanese clan which claims descent from Emperor Seiwa, and is a branch of the Minamoto clan. They were famous for their role as retainers of the Takeda clan in the 16th century. In the Edo period, the clan produced two "daimyō" families: one ruling the Aizu domain, the other one ruling the Iino Domain. The Aizu-Matsudaira were descended from Hoshina Masayuki, a son of Tokugawa Hidetada, adopted by Hoshina Masamitsu.