A further depreciation of the yen won’t be good for Japan’s economy and may prompt a shift in the central bank’s messaging, according to a former Bank of Japan official, speaking after the currency set a fresh low of more than five years.

"The yen has already moved a lot compared with last year, so a further weakening means volatility has generally been high. That isn’t at all desirable,” Kazuo Momma, a former top official in charge of monetary policy at the BOJ, said in an interview.

Until now the central bank has appeared to emphasize that a weak yen is positive for the economy overall, but it may need to shift the nuance of its communications on that point, he said.