 Takaaki was the ninth son of Ishikawa Yoshimitsu, a "hatamoto" from a cadet line of the Date clan of Sendai Domain.In 1868, his step-brother Tamura Kuniyoshi was forced to abdicate due to his role in leading the domain against the new Meiji government in the Boshin War, and the clan elders were forced to quickly select a successor.Takaaki became "daimyō" at the age of 10; however, the following year the title was abolished, and he became domain governor.