Nee Nishida Terumi (西田栄美). Married to Koyama Ryugo in 1993. As a result, her legal name became Koyama Terumi, but she continued to use her born surname, Nishida, as a Go professional. Then, she changed her name to Koyama Mitsuru (滿鶴) in 1999. In 2002, she changed her name again, to Koyama Terumi, finally matching her legal name. Koyama Kuya is their son.
Koyama was the Women's Meijin title holder in 1996-1998 and 2005.