Japan has finally launched formal discussions on how to secure a stable succession to the Chrysanthemum Throne amid a shrinking number of heirs, with options including allowing women to reign and emperors to descend from the maternal line to secure the future of the world's oldest hereditary monarchy.

A six-member government panel held its first meeting on March 23, with its chairman, Atsushi Seike, a former Keio University president, vowing to hold "careful discussions" without haste.

Prime Minister Yoshihide Suga (3rd from L) attends the government's advisory panel on securing a stable line of imperial succession, which held its first meeting in Tokyo on March 23, 2021. (Kyodo)

But the clock is ticking for the family, which is now left with just three male heirs as women marrying commoners have to abandon their imperial status under current rules.

A former senior government official warned that the unbroken line of emperors, which is traditionally said to stretch back more than 2,600 years although some of the earliest figures are viewed as legendary, could very well end in the not-so-distant future unless the government acts swiftly.

Currently, the three heirs in line to succeed 61-year-old Emperor Naruhito are his brother Crown Prince Fumihito, 55, his nephew Prince Hisahito, 14, and his uncle Prince Hitachi, 85.

Japanese Emperor Naruhito and Empress Masako on Nov. 8, 2020, attend a ceremony called "Choken no gi" at the Matsu no Ma stateroom of the Imperial Palace in Tokyo. During the ceremony, Crown Prince Fumihito thanked the imperial couple following the formal declaration earlier in the day of him as first in line to the Chrysanthemum Throne. (Pool photo) (Kyodo) ==Kyodo

The imperial family has been shrinking under the 1947 Imperial House Law, which limits heirs to a male who has an emperor on his father's side. The emperor and Empress Masako's only child is a daughter, Princess Aiko, 19.

The male succession rules have been questioned before, most notably under the government of Prime Minister Junichiro Koizumi in 2005 when an expert panel called for allowing women to succeed to the throne as well as scrapping the rule allowing descent only through the male line.

In Japan, there have been eight female monarchs between the sixth and 18th centuries. But none of them was from a female line of descent.

But the debate quickly lost steam when Prince Hisahito was born in September 2006 as the first new male member of the imperial family in nearly 41 years. He is currently the only unmarried male in the household.

The government of Prime Minister Yoshihiko Noda led by the now-defunct Democratic Party of Japan proposed in October 2012 enabling female members of the imperial family to establish their own imperial branches even after marriage to commoners.

But the momentum for discussions faded after Noda was replaced by Prime Minister Shinzo Abe of the Liberal Democratic Party about two months later.

When the Diet passed legislation in 2017 to allow the abdication of former Emperor Akihito, it attached a nonbinding resolution urging the government to "swiftly consider" measures for realizing a stable imperial succession and creating a system in which women can remain in the imperial family after marriage.

The former emperor, 87, had indicated his wish to step down due to failing health in 2016. He relinquished the throne in 2019 -- the first emperor to do so in around 200 years -- to be succeeded by his eldest son.

But according to sources close to the matter, Abe's government did not see the issue as a pressing matter, with Abe telling experts on a government panel set up in 2016 to discuss Emperor Akihito's abdication that measures to address the problem could wait another 40 years as the crown prince and his son Prince Hisahito would inherit the throne.

Abe also said while dining with the panel members in February 2017 that no decision could be made at the current time due to "clashing" opinions between those who call for maintaining patrilineal inheritance and those who would allow maternal-line emperors, according to the sources.

Abe even left them exasperated by saying a "kamikaze" (divine wind) would "blow when the time comes" and miraculously solve the problem. His comment was a reference to a pair of typhoons that each fortuitously dispersed a Mongol invasion fleet threatening Japan in 1274 and 1281, which came to be known as kamikaze.

The government of Prime Minister Yoshihide Suga, who succeeded Abe last September, has also lacked enthusiasm on imperial matters and been cautious about a major change, according to sources close to the premier.

Speculation is rife that the latest expert panel will not reach a conclusion before a House of Representatives election that must be held by the fall of this year.

But interested or not, the Suga government must make decisions necessary for sustaining the imperial family.

Suga has repeatedly said he will consider the significance of the unbroken history of patrilineal succession despite the overwhelming majority of the public supporting the ideas of having reigning empresses and matrilineal inheritance.

A Kyodo News poll conducted in spring last year found 85 percent of respondents support having an empress on the throne and 79 percent are in favor of emperors in the female line of descent.

When the government unofficially held hearings from experts in the spring of 2020, some were strongly against the ideas of having female monarchs and emperors of matrilineal descent, saying they would "destroy" a Japanese tradition, according to sources familiar with the matter.

Photo shows Atsushi Seike, a former Keio University president, and the chairman of a six-member government panel in Tokyo on March 23, 2021. (Kyodo)

Those experts instead called for adopting into the imperial family some male patrilineal descendants of former branches of the imperial family who abandoned their status in 1947, two years after the end of World War II.

The current Imperial House Law bans adoption into the royal family. In November 2019, a conservative group within the LDP called for enabling unmarried male members of the former branches to join the imperial family through adoption or marriage, if they want to.

LDP conservatives have rejected the idea of allowing female members to remain in the imperial family after marriage, fearing it could pave the way for woman monarchs and those who have emperors only in the matrilineal line.

Those conservatives favor a system under which a new honorific title would be given to female imperial family members who lose their royal status after marriage to enable them to engage in public duties. However, opposition lawmakers are critical of that idea, saying it would only serve as "a stopgap measure."

But even if it opts to allow female monarchs or emperors in the maternal line, Japan must act fast before female members, including Princess Aiko and Crown Prince Fumihito's two daughters -- Princess Mako, 29, and Princess Kako, 26, -- marry out of the family under the current system.

Seike told reporters after the first meeting of the panel, "There are various opinions and we can at least sort out the advantages and disadvantages of each position."