Emperor Naruhito, who took over the imperial throne in May from his father, now Emperor Emeritus Akihito, formally proclaimed his enthronement at a ceremony last Tuesday with a pledge that he will “act according to the Constitution and fulfill my responsibility as the symbol of the state and of the unity of the people of Japan.” Just like his father did when he took the throne for the first time under the postwar Constitution 30 years ago, Emperor Naruhito is expected to continue exploring his role as “the symbol of the state.”

Today, however, the imperial family under the postwar system faces a host of challenges for its future, including questions about stable succession under the current male-only rules and sustainability of the family’s functions amid its shrinking membership. Since Emperor Akihito indicated in 2016 his wish to abdicate — which was not provided for under the law on imperial succession — citing his advancing age, these questions have been highlighted but never officially addressed, as the government concentrated on enacting special one-off legislation paving the way for his abdication, and on the subsequent enthronement of Emperor Naruhito.

The festive public atmosphere celebrating the new emperor and the new era of Reiwa under his reign also appears to have temporarily put aside those questions. Now that the enthronement ceremony is behind us, however, there is no reason to keep putting off public discussions on the issues that concern the very future of the imperial family.

The Imperial House Law limits successors to the throne to male members of the family born in the paternal lineage. Right now, there are only three such members — Crown Prince Akishino, the 53-year-old brother of the emperor, Prince Hisahito, the 13-year-old son of the crown prince, and Prince Hitachi, the 83-year-old brother of the emperor emeritus. Prince Hisahito, who was born in 2006 as the first boy born to the imperial family in 40 years — and the first since the birth of his father — is the sole male member of the family of his generation. As the situation stands now, the pressure to keep up the male-only line of succession will eventually fall on him alone.

Currently, there are 18 members of the imperial family, including Emperor Naruhito and Empress Masako as well as Emperor Emeritus Akihito and Empress Emerita Michiko. The family has six unmarried female members, including the emperor’s 17-year-old daughter, Princess Aiko. The Imperial House Law dictates that the female members will lose their imperial status once they marry someone outside the family. Unless the rule is changed, the imperial family membership is set to shrink, which will make it increasingly difficult for the family to keep up many of its public functions.

In 2012, the Democratic Party of Japan-led administration compiled a report on the creation of new imperial houses led by female members so they would retain their imperial status after marrying someone from outside the family. But the idea went nowhere with the DPJ’s fall from power, and opposition remains strong among conservative lawmakers within the ruling Liberal Democratic Party. They fear this could lead to the enthronement of a reigning empress and imperial succession in a maternal line. Prime Minister Shinzo Abe himself repeatedly emphasizes that the imperial throne has been handed down through the family’s paternal lineage throughout its history.

Japan had eight reigning empresses (two of them enthroned twice) up to the 18th century, but all of them had an emperor in their paternal lineage. No imperial succession has taken place via the family’s maternal lineage. In 2005, a private advisory panel to Prime Minister Junichiro Koizumi compiled a report that recommended allowing the enthronement of a reigning empress and succession via maternal lineage in response to the declining ranks of potential male heirs to the throne. The discussion was shelved when Prince Hisahito was born to the Akishino house the following year. Today, however, roughly 70 percent of respondents in media surveys support a reigning empress or maternal lineage succession.

The conservative lawmakers of the LDP meanwhile advocate a solution to the problem by bringing male members of former imperial houses — who left the family during the Occupation period immediately after World War II — back into the family as potential heirs to the throne. Abe once mentioned this option but told the Diet last March that the government is not contemplating this idea.

A supplementary resolution to the special legislation on Emperor Akihito’s abdication calls on the government to discuss measures for ensuring stable imperial succession promptly after the abdication has taken place and report to the Diet. The government reportedly plans to launch a panel of experts to study the matter after the Daijosai offering ceremony next month, although some media reports say that may be delayed until next spring. Given how the issue has long split the political spectrum, there is little prospect that consensus will be reached anytime soon. But it is not an issue that will be resolved with the sheer passage of time, either.

Under the Constitution, the emperor’s position as symbol of the state derives from “the will of the people.” A broad-based discussion should be launched on the questions that concern the future of the imperial system in ways that reflect the popular will.