Japanese Emperor Akihito intends to abdicate eventually, public broadcaster NHK said on Wednesday, a step unprecedented in modern Japan.
The 82-year-old monarch has spent much of his 27-year reign working to heal the wounds of a war waged across Asia in his father's name and helped bring the monarchy closer to ordinary citizens.
Akihito, who has had health problems in recent years, expressed his intention to the Imperial Household Agency, NHK said, adding he wanted to step down "in a few years". It did not cite a reason.
Officials at the agency could not immediately be reached for comment.
Born in 1933, he was heir to Emperor Hirohito, in whose name Japan fought World War Two. His heir is Crown Prince Naruhito, 56.
Akihito marked the 70th anniversary of World War Two's end with an expression of "deep remorse", a departure from his previous remarks seen by some as an effort to cement a legacy of pacifism under threat from conservative Japanese nationalists.
"Looking back at the past, together with deep remorse over the war, I pray that this tragedy of war will not be repeated and together with the people express my deep condolences for those who fell in battle and in the ravages of war," he said on August 15, 2015, the 70th anniversary of the war's end.
A scientist by avocation, Akihito is the first royal heir to have married a commoner. Under the postwar constitution, the emperor is "the symbol of the State and of the unity of the People," with little formal power.
His efforts to draw the imperial family closer to the people in image, if not in fact, have played into a carefully crafted picture of a "middle-class monarchy" that has helped shield it from the harsh criticism suffered by flashier royals abroad.