Never thought they did, but jolly thoughtful of the MOF to confirm as much.
USD/JPY dropped to a 14-year low of 84.82 on November 27. when there were reports the Japanese authorities had called banks to check dollar/yen rates.
Last time Japanese authorities intervened to buy USD/JPY was back in March 2004.
USD/JPY sits presently at 92.15, effectively unchanged on the day.