He is currently serving as an executive director of the Japan Shogi Association.

[1] Nishio was born in Yokohama, Kanagawa Prefecture on September 30, 1979.

[2] He finished runner up in the Elementary School Student Meijin Tournament [ja] in 1988 as a third-grade elementary school student, and made the semi-finals of the same tournament two years later.

He was promoted to the rank of 1-dan in 1995, and obtained full professional status and the rank of 4-dan in April 2003 after finishing runner up in the 32nd 3-dan League with a record of 11 wins and 7 losses.

[3][4] Nishio's promotion history is as follows:[5] Nishio was elected to the Japan Shogi Association's board of directors for a two-year term as an executive director in June 2019.