The future of Japan's monarchy was thrown into confusion yesterday when the national broadcaster reported that Emperor Akihito was planning to abdicate after 27 years on the throne.
No Japanese monarch has abdicated for almost two centuries and the revered Emperor symbolises national stability and continuity.
Yet both NHK, the national broadcaster, and Kyodo News, a major news agency, reported that Emperor Akihito, 82, was planning to step down in the near future to make way for his son.
The Imperial Household Agency took the unusual step late yesterday of issuing a categorical denial. "It is absolutely not true," said Shinichiro Yamamoto, the Vice Grand Steward.
He added that the Emperor, who has been in poor health for several years, has "long refrained" from discussing any issues of this kind out of "consideration for His Majesty's constitutional position".
But observers believe that neither NHK nor Kyodo News would have taken the risk of reporting such claims without strong sources.
The Emperor's reported plans have triggered more stories in the Japanese media, with Yomiuri Shimbun, the nation's biggest-selling newspaper, claiming that he has secretly reviewed the possibility of stepping down.
With a history of 2,600 years, the Japanese monarchy is believed to be the oldest in the world. If the Emperor wanted to abdicate, the law would have to be revised in order to permit him to do so.
There would be other complications. His successor and eldest son, Crown Prince Naruhito, only has a daughter. The idea of Japan having an Empress would provoke strong opposition, particularly within the conservative ruling party.
In a reflection of the sensitivity surrounding the issue, Shinzo Abe, the prime minister, and Yoshihide Suga, the government's spokesman, have both declined to comment.
Emperor Akihito inherited the throne 27 years ago. His late father, Hirohito, led Japan to catastrophe in World War II and was treated as a living God, until his powers were relinquished in 1945.
Today, the Emperor's position is purely symbolic with no direct political power, although he serves as the head of Japan's Shinto religion.
Emperor Akihito has been something of a reformer. He was the first Japanese monarch to marry a commoner and the first to visit China, publicly acknowledging that his country had inflicted "great suffering" on its neighbour during World War II.
But he has been in frail health in recent years. In 2003, he was diagnosed with prostate cancer. He suffered a stress-related illness in 2008 and then received heart bypass surgery in 2012.
As long ago as 2009, the Imperial Household Agency announced that the Emperor would be reducing his official duties. Crown Prince Naruhito, 56, has assumed a more prominent role, often attending events on behalf of his father.