水戶藩
was a Japanese "daimyō" of the mid-Edo period, who ruled the Mito Domain. He was the son of Matsudaira Yoritoyo, the lord of the Takamatsu Domain. His childhood name was Matsudaira Kemaro (松平軽麻呂) later changed to Tokugawa Tsuruchiyo (徳川鶴千代).