[1] She was born the eldest daughter of Okita Katsujirō, in a samurai family from Mutsu Province.

In 1868, during the Boshin War, Sōji was suffering from tuberculosis and thus stayed with Mitsu and her family in Edo, while the rest of the Tokugawa shogunate forces retreated to the Tohoku region.

Mitsu looked after the terminally ill Sōji, until she and her family were forced to evacuate to Shonai han.

Her husband died in 1883, and she went to live with her youngest son in Manchuria.

In the 2004 Taiga drama Shinsengumi!, she was portrayed by Yasuko Sawaguchi.