TOKYO -- The ascension of the new emperor has left Japan with just three eligible heirs to the throne, raising serious concerns about stable Imperial succession and likely rekindling a debate about expanding the role of royal women, including allowing female emperors.
But such a change is firmly opposed by traditionalists within the ruling Liberal Democratic Party, and Prime Minister Shinzo Abe remains reluctant to embrace the idea, making an immediate change unlikely.
The 2017 legislation that permitted now-Emperor Emeritus Akihito to abdicate called for the government to consider ways to address the succession issue "speedily" after the law's implementation and report its findings to parliament. The legislation specifically mentions the possibility of allowing women to remain in the Imperial family after marriage and form their own houses.
Chief Cabinet Secretary Yoshihide Suga called the succession problem "extremely important" when he spoke with reporters on May 1, but said the government's immediate priority is to "ensure the ceremonies for His Majesty's accession go off without a hitch." He seems to indicate serious discussion of the issue would wait until after the succession rites end in the fall.
The law governing Imperial succession states that the throne "shall be succeeded to by a male offspring in the male line." Japan had ruling empresses during the Nara period in the seventh and eighth centuries, and again during the Edo period in the 17th and 18th centuries, before the current law was put in place after World War II. But every ruler to date, male and female, has come from the paternal line of descent.
The three remaining heirs are Naruhito's younger brother, Crown Prince Akishino, 53; Akishino's son, Prince Hisahito, 12; and Prince Hitachi, the retired emperor's younger brother, who is 83 years old.
The shrinking size of the Imperial family creates problems beyond the line of succession. With fewer family members, more duties fall on the shoulders of each individual. And six of the 18 remaining members are unmarried women, who would lose their royal status if they wed commoners.
Tokyo has debated how to deal with the succession problem for years. In 2005, an expert panel formed by then-Prime Minister Junichiro Koizumi recommended that Japan switch to a system of primogeniture -- favoring the emperor's firstborn child regardless of gender. This would open the door to both female rulers and -- if a ruling empress is succeeded by her child -- matrilineal heirs.
Though Koizumi himself was willing to make such a change, the idea met with resistance from many lawmakers and cabinet members from the conservative LDP. The discussion lost momentum after news emerged in February 2006 that Akishino's wife, Kiko, was expecting another child. That the child turned out to be a boy appeared to defuse the potential succession crisis for the time being.
The issue resurfaced after the more liberal Democratic Party of Japan took power a few years later. After consulting with experts in fields including the constitution and religion -- in light of the emperor's ceremonial role in Japan's Shinto religion -- Prime Minister Yoshihiko Noda in October 2012 drew up a proposal to allow female-led Imperial houses.
Plans to submit the measure to parliament were shelved after the DPJ was trounced by Abe's LDP in elections that December. Abe had been critical of the proposal as opposition leader, arguing that it risked undermining a "basic principle of the history and tradition of the Imperial family."
Abe remains reluctant to change the current system. In a March budget committee meeting, he said the matter must be "carefully and respectfully considered, bearing in mind the weight of the fact that patrilineal succession has been maintained without exception from ancient times."
The government must analyze the issue fully and proceed cautiously in order to build a public consensus, he said.
The new emperor received the Imperial regalia in a succession ceremony on May 1. As when the rite was conducted in 1989 for Akihito, no female Imperial family members were in attendance. The government likely decided that letting female royals be present for the handover of the proof of Imperial succession could have suggested support for allowing women or matrilineal heirs to take the throne.
"There's no need to rush to discuss female-led Imperial houses or ruling empresses when there's a legitimate heir in Prince Hisahito," a senior Cabinet Secretariat official said. "It's hard for momentum to build toward changing the system as long as there's no pressing problems such as a further decline in male Imperial family members in the line of succession."