A decade ago, Bank of Japan Gov. Haruhiko Kuroda won praise for ending a debilitating spike in the yen with his "bazooka" stimulus.

Now the currency's slide is putting him under siege and forcing him to reluctantly concede that once he leaves next April, the bank may start relaxing its policy that caps bond yields.

True to his dovish streak, Kuroda told a briefing last week the BOJ's guidance to keep policy rates at "current or lower levels" won't change for about two to three years — well beyond the end of his second, five-year term in April.