If the pope can retire, why can't Japan's elderly emperor?

wanted to abdicate "in a few years", something unprecedented in modern Japan.

Ordinary Japanese sympathize with his apparent desire to hand over to Crown Prince Naruhito but the idea faces stiff opposition from Prime Minister Shinzo Abe's conservative base.

Conservatives have already raised objections to changing the law to let Akihito step down, citing problems ranging from his title and possible strife with a new emperor, to worry the next step would be letting women succeed and pass on the throne, anathema to traditionalists.

Even more, conservatives fear that a debate over the imperial family's future would divert political energy from Abe's push to revise the postwar, pacifist constitution, which they see as a symbol of defeat, but admirers consider the guarantor of Japan's democracy.

Abe's ruling bloc and allies last month won a two-thirds majority in parliament's upper house, which, with a similar grip on the lower chamber, clears the way to try to change the charter. Revisions also require approval by a majority in a referendum.

"For the first time since the war's end, there is a chance for the Japanese people to revise the constitution that was forced upon them by Occupation forces," said Akira Momochi, a conservative constitutional scholar at Nihon University.

"Frankly, I worry we will lose the ability to achieve this."

Once considered divine, the emperor is defined in the constitution as a symbol of the "unity of the people" with no political power.

Akihito became emperor after the death in 1989 of his father, Hirohito, in whose name Japan fought the war. He has sought to soothe the wounds of that conflict and tried to bring the monarchy closer to the public.

Unlike some European monarchies, Japan has no legal provision for abdication, though many emperors abdicated in the pre-modern era.