There is almost no way the central bank can hit the two-year, 2 percent inflation target Kuroda set when he unleashed unprecedented monetary stimulus in April 2013. Economists think it is unlikely to even get close in the foreseeable future.
That could undermine Kuroda's so far unchallenged authority to implement radical policies and cast doubt on his money-printing drive to revive Japan's economy, interviews with more than a dozen current and former BOJ officials and insiders show.
"The board members gave Kuroda's experiment a one-year moratorium," said a former central bank board member who still has close contacts with incumbent policymakers. "They decided to wait-and-see for a year. But now it's time of reckoning."
A divided board could undermine the public confidence essential to Kuroda's success in embedding expectations of inflation, and leave markets fretting about how authorities will deal with the central bank's massively expanded balance sheet.
Kuroda has been relentlessly optimistic even as the economy, hit by a sales tax hike in April, flirts with recession and falling oil prices threaten to pull inflation below 1 percent.
But most of his policymaking board has always been quietly skeptical of his signature "quantitative and qualitative easing" (QQE), a policy that floods liquidity into the banking system to end 15 years of falling prices, and now the fissures are widening.
Kuroda says inflation will accelerate again, but also that the BOJ will expand monetary stimulus should the 2 percent target be at risk - something many on the board question.
People close to Kuroda say his conviction the BOJ can meet its inflation target is genuine and not just aimed at boosting sentiment, and that the governor still sees the next policy move as an exit instead of a further expansion of stimulus.
The chance of open revolt against the governor is slim, in part because there is no consensus among the dissenters and Kuroda can count on the support of his two deputies, who were appointed around the same time as him.
But the board's two market economists and two businessmen are either skeptical of QQE or hesitant to maintain it for too long. The two academics are hard to predict.
The doubts about the current stimulus signal that the prospect of further easing is also anathema to some, who say the BOJ is already struggling to force-feed free cash to markets. It has had to contend with negative interest rates at some debt auctions.
"Many are confused as to what to do next," said one official familiar with the board's deliberations.
The BOJ policymakers are set to maintain their upbeat price forecasts at a rate review on Friday, as ditching them could stir unwelcome market speculation of immediate monetary easing.
But skeptics of the current framework may propose ditching the two-year time frame for meeting the target, by using more ambiguous language to explain when the price goal may be met.
In a hint in that direction, Deputy Governor Kikuo Iwata told parliament on Tuesday that there was uncertainty on exactly when inflation would hit 2 percent. "It's not set in stone like a train timetable," Iwata said.
While there is no consensus on the matter yet, discussions may kick off on Friday and intensify in coming months, particularly if economic growth remains anemic.