Prime Minister Shinzo Abe's government nominated an international finance researcher to the Bank of Japan's divided board to fill the seat of a retiring member who recently voted against expanding monetary stimulus.

Makoto Sakurai, 70, of the Sakurai Associates International Finance Research Center, is to fill the seat of Sayuri Shirai, 53, whose term ends on March 31. Shirai, who is the only woman on the board, opposed the adoption of the negative-rate policy in January. She had voted with Gov. Haruhiko Kuroda to expand asset purchases in 2013 and again in 2014.

The change in the central bank's board comes as its negative-rate strategy generates controversy at home and abroad and as inflation remains far from the BOJ's 2 percent target. The board's composition is increasingly important for policy with the last expansions of stimulus passing by votes of 5 to 4.