Japan's Emperor Akihito made a rare televised address to the nation, in which he expressed concern about fulfilling his duties as he ages – although he stopped short of saying he might abdicate. Now aged 82, the emperor said: "Fortunately I am now in good health. However, when I consider that my fitness level is gradually declining, I am worried that it may become more difficult for me to carry out my duties as the symbol of the state."

The speech was seen in part as an attempt to explain why he might want to abdicate, and presumably win public understanding when the time comes. Public broadcaster NHK reported last month that Akihito, who has had heart surgery and been treated for prostate cancer, wanted to step down in a few years – a move that would be unprecedented in modern Japan.

Born in 1933, Akihito was heir to Emperor Hirohito, in whose name Japan fought World War Two. Akihito is the first royal heir to have married a commoner, Michiko Shoda, the daughter of a wealthy industrialist.

Japan Emperor Akihito
20 November 1949: Crown Prince Akihito looks on as his father, Emperor Hirohito, reads a newspaperAFP
Japan Emperor Akihito
10 April 1959: A wedding photo of Crown Prince Akihito and Michiko ShodaPublic domain
Japan Emperor Akihito
10 April 1959: Crown Prince Akihito and Crown Princess Michiko parade through the streets of Tokyo on their wedding dayKyodo/Reuters
Japan Emperor Akihito
28 December 1977: Emperor Hirohito and his family welcome the New Year at the Imperial Palace in Tokyo. From left are Princess Hitachi, Prince Hitachi, Prince Aya, Emperor Hirohito, Empress Nagako, Prince Hiro, Princess Nori, Princess Michiko and Crown Prince AkihitoAFP
Japan Emperor Akihito
12 April 1986: Emperor Hirohito of Japan is pictured in TokyoReuters
Japan Emperor Akihito
12 November 1990: Japanese Emperor Akihito wears a full ceremonial outfit during his enthronement ceremony at the Imperial PalaceAFP

Akihito has sought to deepen Japan's ties with the world through visits abroad. In 1992 he became the first Japanese monarch in living memory to visit China, where bitter memories of Japan's past military aggression run deep.

Japan Emperor Akihito
24 October 1992: Emperor Akihito and Empress Michiko tour the Badaling section of the Great Wall of China, northwest of BeijingMike Fiala/AFP
Japan Emperor Akihito
9 June 1993: Prince Naruhito and his wife Crown Princess Masako pose with Emperor Akihito and Empress Michiko after their wedding at the Imperial PalaceImperial Household Agency/Getty Images
Japan Emperor Akihito
13 June 1994: US President Bill Clinton bows to Japanese Emperor Akihito during welcoming ceremonies at the White HousePaul J Richards/AFP
Japan Emperor Akihito
29 May 2007: Emperor Akihito and Empress Michiko are welcomed to Buckingham Palace by Britain's Queen Elizabeth IIFiona Hanson/AFP
Japan Emperor Akihito
14 November 2009: US President Barack Obama bows to Emperor Akihito upon arriving at the Imperial Palace in TokyoJim Young/Reuters
Japan Emperor Akihito
12 December 2009: The Japanese imperial family visit visit Kodomonokuni, or Children's Land, in Yokohama to mark the 50th wedding anniversary of the emperor and mpress. Front row: Emperor Akihito and Empress Michiko, and then working towards the back of the train: Crown Prince Naruhito and Crown Princess Masako, Prince Akishino, Princess Kako, Princess Kiko and Prince HisahitoShuji Kajiyam/Reuters
Japan Emperor Akihito
27 April 2011: Emperor Akihito and Empress Michiko visit Minamisanriku in Miyagi Prefecture, which was devastated by the 11 March earthquake and tsunamiToru Yamanaka
Japan Emperor Akihito
19 June 2012: Emperor Akihito and Empress Michiko leave after praying at the altar of late Prince Tomohito, a cousin of the Emperor, in TokyoItsuo Inouye/Reuters
Japan Emperor Akihito
11 March 2013: Emperor Akihito and Empress Michiko bow as they pay tribute to the victims of the 11 March 2011 earthquake and tsunami at the national memorial service in TokyoJunji Kurokawa/Reuters
Japan Emperor Akihito
12 April 2013: Emperor Akihito and Empress Michiko dance at a charity function at a hotel in TokyoKyodo/Reuters

He marked the 70th anniversary of the end of World War Two with an expression of "deep remorse", a departure from previous remarks that was seen by some as an effort to cement a legacy of pacifism under threat from conservative Japanese nationalists.

Japan Emperor Akihito
15 August 2015: Emperor Akihito and Empress Michiko bow during a memorial service for war victims in Tokyo, to mark the 70th anniversary of the end of World War IIToru Yamanaka/AFP
Japan Emperor Akihito
7 August 2016: Emperor Akihito makes a rare video address to the nation from the Imperial Palace in Tokyo. He said he is worried that age may make it difficult for him to fully carry out his dutiesImperial Household Agency/Getty Images

Opinion polls show the vast majority of ordinary Japanese sympathise with the emperor's desire to retire, but this would need legal changes.