Ii Naomasa
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.