People are living longer than they used to, as any reader of the obituary page can attest. But pushing the threshold of old age ever higher, or surviving to some unprecedented milestone, has problems of its own—as people at the top of the pyramid can attest.

The Scrapbook was pleased to note when Britain's Queen Elizabeth II passed her ancestor Victoria's tenure on the throne and reached the age of 90. But even Her Indefatigable Majesty faces reality: There may well come a time when the queen will be unable to carry out her duties in a country where there is hardly a tradition of abdication. No doubt the unwritten British constitution will find a way around the problem. In the distant past, ­others served as regents when children ­inherited the throne—or, in the early 19th century, when George III's illness incapacitated him.

Of course, in those European states where crowned heads still reign—Norway, Spain, the Netherlands, Denmark, etc.—tenure on the throne tends to be treated like the chairmanship of a board: In the past couple of years, the kings and queens of Spain, the Netherlands, and Belgium have stepped down to make way for younger successors, and even Pope Benedict XVI felt obliged, in 2013, to take the unprecedented step (in modern times) of stepping aside.

Now comes the 82-year-old Emperor Akihito of Japan, who, last week, delivered a 10-minute video message—only the second such occasion in his 27-year reign—which amounted to a plea to be allowed to retire. There is no inside story or unmentioned detail here: The emperor is an intelligent, popular, and deeply conscientious monarch; but in the past decade, he has undergone cardiac surgery and been treated for prostate cancer. And what the Japanese throne lacks in ­political power is more than compensated by heavy, and unrelenting, public duties. By any measure, Akihito has earned the right to shift the burden to his son, the 56-year-old Crown Prince Naruhito.

The problem is that ­Japan's constitution, written during General Douglas Mac­Arthur's postwar Allied occupation, has no provision for an emperor's abdication. And while public sentiment is on Akihito's side, concern is being expressed, from varying perspectives, that one effort to amend the law will open the door to others: to allow women to inherit the throne, for example, or to change the emperor's status from "symbol of state" to "head of state."

Which, given the customary pace of change in Japan, may prolong the process beyond Akihito's reign—and that's too bad. The country is at a crossroads in its modern history: America seems to be retreating from Asia, China is growing increasingly aggressive, and Japan's sclerotic ­political system may not even be prepared to grant an elderly man his well-earned rest.