Nakai also is a former representative director of the Ladies Professional Shogi-player's Association of Japan (LPSA).

In 1983, she entered the Japan Shogi Association's apprentice school and reached the rank of 2-kyū before deciding to leave in 1990.

[2] Nakai was awarded the rank of women's professional 2-kyū by the Japan Shogi Association in April 1981 at the age of 11 as a protegee of Yūji Satō [ja].

The following year the roles were reversed with Nakai successfully defending her title against the challenger Kobayashi three games to two.

[4]: 24 [5] In 2003, Nakai became the first women's professional to win a NHK Cup TV Shogi Tournament game.

[15] Nakai's challenge, however, was unsuccessful as she lost the 48th Kurashiki Tōka Cup title match against Kana Satomi 2 games to none.

[1][3][17] Nakai was selected to be the first representative director of The Ladies Professional Shogi-player's Association of Japan (LPSA) after it was established in 2007, and served in that capacity until 2010.