The government's nomination Friday of Masaaki Shirakawa, a former Bank of Japan executive, and Takatoshi Ito, a member of the government's Council on Economic and Fiscal Policy, as new BOJ deputy governors prompted analysts to wonder whether one of them may become the central bank's chief five years from now.

"It is a possibility," said Susumu Takahashi, vice chairman of Japan Research Institute. "But it all depends on what the two would do during the five years."

Their nomination needs to be endorsed by the Diet, along with the BOJ governor nominee, Toshiro Muto.