Ōyama Iwao
Yamakawa's sisters, Yamakawa Futaba (1844 – 1909) and Yamakawa Sutematsu (1860-1919), later Princess Ōyama Sutematsu (大山 捨松), are also well-known. Futaba, who fought in the Battle of Aizu during the Boshin War, later worked at the Tokyo Women's Normal School (東京女子高等師範学校, Tōkyō Joshi Kōtō Shihan Gakkō), the forerunner of Ochanomizu University. Sutematsu was one of five Japanese girls sent to the United States as part of the Iwakura Mission; she was the first Japanese graduate of Vassar University, and later became the wife of Imperial Japanese Army general Ōyama Iwao.