TOKYO -- Japan's new Emperor Naruhito said in 1985 that he had learned to think for himself after two years at Oxford, apparently declaring his independence from forces trying to control him.

Naruhito, now 59, put his words into practice in 1993 by choosing a U.S.-educated diplomat as his wife, sparking a national sensation and putting the world's oldest monarchy under a spotlight that remains bright to this day.

The couple's life over the last quarter-century -- conceiving a daughter but not a son, Empress Masako's struggles with depression and Naruhito's steadfast support for her -- has fueled an intense public debate about the role of female royals. The biggest question of all has been whether to break with custom and allow a woman to take the throne.

The weight of tradition will be on full display on Tuesday, when Naruhito attends an elaborate enthronement ceremony.

Naruhito will report his accession to the sun goddess Amaterasu, from whom the Imperial family is said to have descended, and declare his accession to a world that already seems intrigued by him. "He is the most cosmopolitan emperor because of his upbringing and overseas education and experience," said Jeffrey Kingston, a professor at Temple University Japan.

"He is intellectually curious and has engaged in environmental issues, and that could become his signature legacy, using his high-profile role to bring attention to an urgent crisis facing the world," Kingston said, referring to Naruhito's lifelong interest in the challenges of water management. In remarks as well as a book, Naruhito has repeatedly noted that too little water breeds conflict while too much causes disasters.

The emperor's modern style and mindset appear to have won support even among scholars close to Prime Minister Shinzo Abe's conservative government.

"Naruhito has struck a good balance between change and tradition," said Hidetsugu Yagi, a professor of constitutional law at Reitaku University and a member of the Abe government's advisory panels on education and the Imperial family. "He has embraced social trends ahead of the times and has fulfilled what the public expects of the Imperial family," Yagi said.

The public role Naruhito is inheriting is very different from what it was in the years before World War II.

U.S. Gen. Douglas MacArthur, left, and Japanese Emperor Hirohito hold an unprecedented meeting at the American Embassy in Tokyo on Sept. 27, 1945. Japan's postwar constitution drastically changed the role of the emperor. © AP

Prewar Japan emphasized the emperor's divinity and used it to obtain the obedience of the people. Though the monarch did not have real authority over the government, policies were implemented in his name.

"The Emperor is sacred and inviolable," the old constitution said. "The Emperor is the head of the Empire, combining in Himself the rights of sovereignty."

The postwar constitution, drafted during the Allied Occupation and said to have been influenced by the U.S., instead placed sovereignty squarely in the hands of the people. The throne comes with no political power and is declared to be a symbol of the unity of the people.

Naruhito's father, Emperor Emeritus Akihito, worked during his reign to embody the spirit of the constitution. He visited countries Japan had invaded, seeking to help heal the wounds of war and spreading a message of peace. It is a message Naruhito clearly took to heart.

"I will reflect deeply on the course followed by his majesty the emperor emeritus and bear in mind the path trodden by past emperors," Naruhito said in his accession address on May 1.

"Looking back, his majesty the emperor emeritus, since acceding to the throne, performed each of his duties in earnest for more than 30 years, while praying for world peace and the happiness of the people, and at all times sharing in the joys and sorrows of the people," he said.

Emperor Akihito visits an evacuation center in northeastern Japan in the aftermath of the March 11, 2011, earthquake and tsunami.

In a country that has been hit by numerous natural disasters in recent years -- none bigger than the 2011 earthquake and tsunami -- Akihito and his wife, Empress Emerita Michiko, tirelessly visited stricken areas and knelt to talk with survivors. Those moments of solace defined the couple in the last years of Akihito's reign, and Naruhito sounds determined to reach his people in a similar way.

Diplomacy is likely to keep him busy, too, Yagi noted. An audience with the Imperial family helps foreign leaders feel closer to Japan, the professor said.

Other official functions include opening the parliament, promulgating laws and appointing the prime minister designated by the parliament. The calendar is typically packed with social events, including visits to various communities, hospitals and schools.

It was at least partly this heavy schedule that prompted Akihito's decision to abdicate at the age of 85 -- the first abdication in Japan's modern history. Though Naruhito was ready to step in, the transition has brought concerns over the future of Imperial succession back to the surface.

Next in line are the emperor's brother, 53-year-old Crown Prince Fumihito, and nephew, 13-year-old Prince Hisahito. After them, according to the law, the only other potential successor is the emperor's uncle, 83-year-old Prince Masahito.

This is the fewest possible heirs in the postwar period, which raises an old but delicate question: Why not have a female emperor?

Traditionalists oppose the idea of a female emperor or allowing someone from a female line to accede to the throne. Though eight of the past 126 emperors have been women, under the current law, succession is limited to male offspring in the male line of the Imperial family.

The traditionalists say changing this now would sow confusion. When confronted with the history of women on the throne, they argue that the women were always from a male line, stayed single during their reigns and always had a male successor in place.

Instead of having female emperors, Yagi said that reviving the former princely houses would immediately increase the number of potential heirs and solve the issue. During the Occupation, the Imperial household was sharply scaled down, with 11 of the 14 princely houses related to the dynasty stripped of their status.

Modernists, on the other hand, argue that a patriarchal system that relegates women to traditional roles is not supported by the public. A Nikkei survey conducted in May seems to back this up: 76% said Japan should change the law and allow female emperors. An even higher ratio, 78%, said they feel attached to the Imperial family.

Reitaku University's Yagi did suggest that women in the Imperial family should no longer be expected to stay in the shadows of men. "In the past," he said, "female royals weren't able to contribute much other than accompanying their husbands. In the future, more opportunities should be created for female royals to shine. They should be encouraged to perform functions on their own without their husbands."

The prospects for tangible change are unclear, however. The debate over female emperors briefly attracted political and public attention after Akihito expressed his will to abdicate in 2016, but the discussion gained little traction.

Meanwhile, a more personal issue looms for Naruhito and Masako -- managing a sometimes uncomfortable relationship with the Imperial Household Agency, a special government body in charge of affairs related to the Imperial family.

At times, the agency has been accused of limiting the family's freedom, so much so that the emperor has been described in Western media as a "prisoner in his own palaces."

In 2003, just before her 40th birthday, Masako was diagnosed with shingles and what was later described as an adjustment disorder, and withdrew from public life. In a news conference the following year, Naruhito hinted at his frustration, which many believe was directed at the Imperial Household Agency.

"It is true there were moves to negate Masako's career and her personality," he said. He added that the then-princess had "totally exhausted herself" trying to adapt to palace life.

Emperor Naruhito and Empress Masako welcome U.S. President Donald Trump and first lady Melania Trump at the Imperial Palace in Tokyo on May 27.

Empress Masako spent much of her childhood overseas due to her father's job in the foreign service. She went to high school in Belmont, Massachusetts, and graduated magna cum laude from Harvard College.

In 2002, she admitted to reporters that she had trouble adjusting to a life that, in effect, confined her to Japan. "In my life before we married, and in my family as I was growing up, there were many occasions to travel abroad," she said. "As such, honestly speaking, during the six years after our previous trip abroad, the fact that it was rather difficult to make visits abroad was something that required a great effort on my part to adapt to."

The head of the Imperial Household Agency remarked in response, "I was surprised to know she wanted to go overseas so much."

Today, Masako still struggles with her illness but is slowly returning to the public eye. Naruhito has suggested the time is ripe for her to make an impact.

"Masako has a lot of overseas experience," he told reporters in February. "In the age of globalization, she will have more opportunities to use her talent." In May, when U.S. President Donald Trump and first lady Melania Trump visited the palace, Masako demonstrated her abilities as a host.

The emperor is known for his devotion to his wife and their daughter, Aiko.

For Emperor Naruhito's part, he has earned a reputation as a dedicated family man -- perhaps too dedicated, some cynics say. While his father seemed to be always out in public, he has been less visible.

But Temple University's Kingston believes his commitment to his family, and the planet, will serve him well.

"His devotion to his family and environmental issues is inspiring, and enables the Imperial household to connect with people and adjust to significant changes in society," Kingston said. This will help the Imperial institution "remain relevant and respected."