Ii clan

Ii clan (Japanese: 井伊氏, Hepburn: Ii-shi) is a Japanese clan which originates in Tōtōmi Province. It was a retainer clan of the Imagawa family, and then switched sides to the Matsudaira clan of Mikawa Province at the reign of Ii Naotora. A famed 16th-century clan member, Ii Naomasa, adopted son of Ii Naotora, was Tokugawa Ieyasu's son-in-law and one of his most important generals. He received the fief of Hikone in Ōmi Province as a reward for his conduct in battle at Sekigahara. The Ii and a few sub-branches remained daimyō for the duration of the Edo period. Ii Naosuke, the famed politician of the late Edo period, was another member of this clan.

The clan claims descent from Fujiwara no Yoshikado, who had been one of the Daijō daijin during the ninth century.