The decision over who will be the Bank Japan's next chief will likely focus on two career central bankers whose different policy approaches and track records could affect the timing of an eventual exit from ultraeasy monetary policy.

As former and incumbent deputy governors, Hiroshi Nakaso and Masayoshi Amamiya have deep expertise in central bank affairs, which makes both of them a safe pair of hands in guiding a future exit from ultralow interest rates, however distant that may be.

Long touted as front-runners in the BOJ leadership race, neither would rush into tightening monetary policy given Japan's fragile economy and the need to keep low the cost of funding its huge public debt, say five former and incumbent policymakers who have worked with or under them.