Japan's Emperor Akihito and Empress Michiko have been on the Chrysanthemum Throne for 27 years after coming to power in 1989
Japan's ageing Emperor Akihito plans to step down in favour of his eldest son within a few years, Japanese media reported Wednesday, in what would be the first such royal abdication in two centuries.
The 82-year-old monarch has told those close to him that his role should be occupied by someone who can fulfil the emperor's duties as stipulated in the constitution, public broadcaster NHK reported, without citing a source for the information.
Under Japan's current Imperial Household Law, which governs the status of the emperor, there is no legal mechanism for abdication.
Any move to step down would therefore require a revision of that law.
Kyodo News agency carried a similar report, citing an unnamed government source.
No one was immediately available at the Imperial Household Agency, which manages Akihito's affairs, or the prime minister's office for comment.
Japan, which claims to have one of the world's oldest monarchies, has not seen an imperial abdication from the Chrysanthemum Throne in 200 years, NHK said.
Akihito's role is strictly limited to one of "symbol of the state" under a constitution imposed by the United States in the aftermath of World War II.
His father Hirohito, in whose name the military conquests of the 20th century were prosecuted, was treated as a living god in Japan until defeat in 1945.
-- 'Feel my age' -
The Japanese throne is held in deep respect by much of the public, despite being largely stripped of its mystique and quasi-divine status in the aftermath of the war.
The revered Akihito, who has suffered from numerous health issues including prostate cancer and heart surgery, publicly hinted late last year at his growing limitations in the performance of his ceremonial duties.
"I am beginning to feel my age, and there were times when I made some mistakes at events," he told reporters at an annual press conference just ahead of his birthday on December 23.
But Kyodo stressed, citing a government source, that there are no health issues that would cause him to have to step down immediately.
The news agency also said that Akihito expressed his wish to abdicate at least one year ago.
Crown Prince Naruhito, the monarch's eldest son, and Empress Michiko, his wife, support the wish, NHK said.
In 2011, Prince Akishino, the emperor's second son, told a press conference that Japan should discuss setting a retirement age for emperors, just days after his father was discharged from hospital.
Though soft spoken, the constitutionally constrained Akihito has managed to push boundaries as both crown prince and emperor.
Empress Michiko was a commoner before entering the imperial family as his wife. The two met on a tennis court and their 1959 marriage was a national sensation.
Akihito has offered subtle hints as to his own views in the nearly three-decade reign.
In an encounter at a 2004 imperial garden party captured on camera he was seen telling a Tokyo municipal official who had pushed for the compulsory use in schools of the Japanese flag and national anthem -- an ode to the emperor -- that such a forced stance was undesirable.
And in 2001 at a press conference ahead of his birthday, he acknowledged that some of his ancient ancestry was traceable to the Korean peninsula, a virtual red flag to arch-nationalists who promote a view of Japan as a nation characterised by a single, pure race.
In remarks in August last year at a memorial marking the 70th anniversary of Japan's 1945 surrender, he expressed "profound remorse" for the war fought in his father's name, reportedly the first time he had used those words at the annual event.