The controversial marriage of Japan's Princess Mako and her university sweetheart Kei Komuro highlights the struggle that members of the royal family have in balancing their public and private lives, in what some pundits have called a "warning sign" for maintaining a monarchy in a modern democracy.

The 30-year-old niece of Emperor Naruhito went ahead with the marriage in an unprecedented manner by skipping the usual traditional rites and turning down a lump-sum payment of up to about 150 million yen ($1.3 million) in taxpayers' money, amid public unease over media reports on a financial dispute involving Komuro's mother.

The Komuro family has become fodder for Japanese tabloid magazines and TV talk shows, leaving many people unconvinced that the Komuros are fit to become relatives of the imperial family, including Princess Mako's younger brother Prince Hisahito, 15, who is seen as a future emperor.

Japanese Princess Mako (R) leaves her family's residence in the Akasaka Estate in Tokyo on Oct. 26, 2021, with her parents Crown Prince Fumihito and Crown Princess Kiko and her younger sister, Princess Kako, seeing her off. The Imperial Household Agency submitted legal paperwork the same day to register her marriage to her commoner boyfriend Kei Komuro on their behalf. (Kyodo) ==Kyodo

The princess abandoned her royal status and became Mako Komuro under a family registry with her university sweetheart as the Imperial Household Agency submitted legal paperwork to register the couple's marriage on their behalf on Tuesday.

Kenneth Ruoff, a professor of modern Japanese history at Portland State University, said, "Princess Mako's marriage is a warning sign," indicating that Japan's imperial system could face a crisis in the future.

Despite a dwindling number of imperial family members, Princess Mako's marriage pointed to the fact that other royal family members -- including male heirs to the throne -- could pursue a life based on their personal choice and leave the household in the future, according to Ruoff.

Related coverage:

Japan's former princess Mako Komuro says marriage "necessary choice"

Celebrations for Princess Mako's marriage muted over money dispute

FOCUS: Princess Mako's marriage casts shadow on imperial succession debate

Currently, Prince Hisahito, who is second in line to the Japanese imperial throne, is the only heir of his generation, as the 1947 Imperial House Law limits inheritance of the Chrysanthemum Throne to a male who has an emperor on his father's side.

"Everybody will be holding their breath, waiting to see if Prince Hisahito can find a wife and have a son," Ruoff said, describing it as "an unbelievable burden on the shoulders of the prince."

Ruoff said in an online interview with Kyodo News that Prince Hisahito might decide in the future that he does not want anything to do with imperial matters and may wish to leave for another country. "That would be a crisis" in maintaining Japan's monarchy, he added.

Although Emperor Naruhito, 61, his wife Empress Masako, 57, and other royal family members do not have direct political functions, they serve as symbolic figures and play an important diplomatic role in the country.

Taxpayers' money covers their living expenses, but their freedoms, such as where to live and work, are greatly restricted compared to ordinary people's lives.

Former princess Mako Komuro (R), daughter of Crown Prince Fumihito, and her husband Kei Komuro hold a press conference in Tokyo on Oct. 26, 2021. (Kyodo)

Comparing the weight of their duties with this lack of freedom, being a member of the royal family is possibly "burdensome" except for those who strongly want to make a difference in the country, Ruoff said.

"Many things such as traveling abroad that used to be open only to the elite, which included the royal family members, are now open to a much broader group of people," Ruoff said, adding that the burdens outweigh the benefits of being a royal member.

An imperial agency official, who asked to remain anonymous, also said, "Not many people understand the fact that the imperial family members live with suppressed freedom and human rights."

In the eye of Japanese citizens, the imperial family has been a symbol of "morality" at the expense of their privacy and freedom, said Hideya Kawanishi, an associate professor at the Nagoya University Graduate School of Humanities who is an expert on imperial affairs.

During his 30-year reign, former Emperor Akihito and his wife, former Empress Michiko, both 87, spent a significant amount of time consoling the victims of disasters, including the March 2011 earthquake and tsunami in northeastern Japan that triggered the Fukushima nuclear crisis.

Related coverage:

PROFILE: Princess Mako's groom Kei Komuro pursuing legal career in U.S.

PROFILE: Princess Mako known as independent, with in-depth knowledge of art

Chronology of major events related to Princess Mako's marriage

"That's why many people felt betrayed by Princess Mako's action (to go ahead with the marriage) as they perceived she strongly pursued her personal wishes even though she was expected to work for the public," Kawanishi said.

Since the revelation of the financial dispute on the Komuro family side after the couple were unofficially engaged in 2017, social media platforms such as Twitter have been flooded with derogatory comments toward them and their families.

In a press conference Tuesday, the princess said she was "horrified, scared and saddened by the fact that false information has been taken as fact and that unfounded stories have spread."

"If I have to pick the biggest concern, it would be continued libel" against the couple and their families, she said, while expressing in a written statement her wish to lead a peaceful life from now on.

The agency had revealed earlier this month that the princess had been diagnosed with complex post-traumatic stress disorder caused by what she described as psychological abuse of the couple and their families.

Another agency official, who asked to remain anonymous, said the princess' illness was induced by "magazines" that fueled concerns over the marriage among the public and "comments made online in response" to the report, which criticized the couple and their families.

The brunt of the criticism was directed at the country's imperial system.

Empress Masako has also been suffering from a stress-induced illness since giving birth in 2001 to Princess Aiko, 19, the only child between her and the emperor amid pressure to produce a male heir.

"Imperial family members including Princess Mako are in a position where they can't easily respond to defamation by themselves," Kawanishi said.

The agency cannot take strong measures such as legal steps to identify those who write derogatory comments, as the imperial system is built on the trust of the public, according to the official.

"Princess Mako's marriage revealed the very important issue about imperial family members' desires and personal choices that we have not thought about sufficiently before," Kawanishi said. "The fact that the issue came to light in the princess' case tells us that we seriously need to think about Japan's imperial system."