Two years after unleashing record monetary stimulus, Bank of Japan Gov. Haruhiko Kuroda and his allies are confronting increasingly vocal opposition from the opponents of reflation who once dominated the policy debate.

Hundreds of economists filed in to a May 16 symposium on BOJ policy at a Japan Society of Monetary Economics semiannual gathering in Tokyo. Backers of Kuroda's 2 percent inflation target squared off against advocates of monetary restraint, who say the BOJ's bond purchases are delaying a crucial overhaul of public finances to deal with record debt.

"The discussion was heated," Masahiko Takahashi, a professor at Yokohama National University who used to work at the central bank, said of the closed-door, two-hour session. "It's been two years since the BOJ started QQE and there's growing interest in the BOJ's monetary policy and its effects," he said, using the initials for Kuroda's stimulus program.