Economists had been expecting a 1.7% increase in output from the manufacturing sector from June, boosted by the effects of reconstruction spending in the tsunami-hit Tohoku area.
Instead, preliminary government data suggested that production sank 1.2% in July. Manufacturers are now forecasting production to increase 0.1% in August, then fall 3.3% in September.
Masamichi Adachi, senior economist at JPMorgan in Tokyo, described the data as "incredibly poor," noting that if manufacturers' forecasts were accurate, industrial production would decline for three consecutive quarters -- a prelude to all five of Japan's recessions since 1985.
If external demand remained downbeat, it would be very hard for Japan to avoid recession number six, the former Bank of Japan official said.