When palace officials informed crown prince Naruhito of the name chosen for Japan’s new imperial era earlier this month, he responded with a nod and the hint of a smile. “I understand,” he said.

A similarly phlegmatic disposition will serve Naruhito well after he is made Japan’s 126th emperor on Wednesday, a day after his father, Akihito, becomes the country’s first monarch to abdicate for more than two centuries.

As Japan prepares to welcome the era of Reiwa – or “beautiful harmony” – experts said they expected the new emperor to continue Akihito’s “people-focused” sense of duty, but with carefully chosen embellishments that reflect his international outlook.

Both men have enduring interests in niche academic subjects. In retirement, the current emperor may choose to add to the 30-plus papers he has written on the classification of goby fish. His son, meanwhile, has demonstrated an interest in water conservation – the legacy of two years he spent in Oxford as a graduate student writing a thesis on the medieval water transport on the Thames.

His time at Merton College appears to have made a lasting impression on the young Naruhito, whose memoirs, The Thames and I, contain fond recollections of pub visits, vinegar-soaked fish and chips, and tussles with an uncooperative washing machine.

Japan’s Emperor Akihito and Empress Michiko pictured in May 2018. Photograph: Franck Robichon/EPA

By the rarefied standards of Japan’s imperial household, Naruhito’s past suggests he will be a thoroughly modern monarch. He is the first Japanese emperor to study abroad and, unlike his predecessors, was brought up among his siblings by Akihito and Empress Michiko, a non-royal who defied tradition by refusing to turn parenting duties over to palace staff.

“I hope to see him develop his own way of doing things in coming years,” Toshio Shiraishi, a longtime friend of Naruhito, told the Associated Press. “The crown prince has closely watched the work of the Showa emperor [Hirohito] and the current emperor and learned from them, while trying to figure out what his role could be.

“He encourages people to talk and helps enrich a conversation. He doesn’t want to be a star; instead he wants to be with people and work together.”

There were distinct echoes of Akihito, who is credited with helping rebuild ties with Japan’s former enemies, in 2015 when Naruhito used his 55th birthday to warn of the need to remember the second world war “correctly”, in a rare foray into an ideological debate.

“Today when memories of war are fading, I believe it is important to look back [at] our past with humility and pass down correctly the miserable experience and the historic path Japan took from the generation who know the war to the generation who don’t,” he said.

Uncertainty surrounds the role of Naruhito’s wife and the future empress, Masako, an Oxford and Harvard-educated former career diplomat whom he married in 1993.

A decade later, it emerged that Masako was suffering from what palace officials described as an “adjustment disorder” brought on by stress. The following year, in unusually candid comments that drew a rebuke from his younger brother, Prince Akishino, Naruhito described Masako’s struggle to adapt to palace life amid mounting pressure to produce a male heir.

“To me, Masako seems to have totally exhausted herself in her efforts to adjust to life as a royal over the past ten years,” he said. “It is also true that there was something that amounted to a denial of her career and personality”. Masako, he added, had felt “anguish” that officials had prevented her from making overseas trips, despite her professional background.

Naruhito and Masako with their daughter Aiko, now 17. Photograph: AFP/Getty Images

The couple have a 17-year-old daughter, Aiko, who cannot become empress, although the pressure on Masako eased slightly when her sister-in-law gave birth to a son, Prince Hisahito, in 2006, just as the government was considering changes to the male-only succession law.

“Masako is a highly intelligent, well-educated woman and, depending on her health, it’s entirely possible that she could do amazing things,” said Christopher Gerteis, associate professor at the Institute for Advanced Studies on Asia at Tokyo University.

“If she takes on an advocacy role for something it will be very well thought out,” Gerteis added. “She could support an organisation like the Japanese Red Cross Society with very little resistance [from the palace].”

In a statement released on her birthday last December, Masako pledged to do her best despite feeling “insecure” about becoming empress, adding that she was recovering and could “perform more duties than before”.

Despite those reassurances, the couple will stagger celebratory banquets involving 2,500 guests planned for this autumn, apparently out of concern for her health.

Naruhito has had more than two years to prepare for his new role, after Akihito used a rare televised address to hint at his wish to retire, fearing his age would affect his ability to carry out official duties.

But any changes in style will be barely perceptible and introduced over time, according to Eiichi Miyashiro, a royal historian and senior staff writer for the Asahi Shimbun newspaper.

“The truth is that we simply don’t know how Naruhito envisages his reign, although there should be some clues in his first statement as emperor,” he said. “We weren’t able to get a clear idea of the current emperor’s style – especially his desire to be closer to ordinary people – until a few years into his reign. I think that will be the case with the next emperor.”

Masako’s role aside, Japan’s imperial household faces long-term uncertainties owing to the lack of male heirs. Currently, only his younger brother, and his son, can succeed Naruhito as emperor.

But for the time being at least, concerns about a potential succession crisis will be set aside as Japan’s people, who have been given an unprecedented 10-day holiday to mark the historical transition, welcome an emperor who, in his own words, has vowed to “share their joys as well as their sorrows”.

In the Shimbashi district of Tokyo, company employee Hiroshi Yamada said he did not expect major changes, but hoped Naruhito would continue his father’s piecemeal modernisation of a deeply conservative institution.

“The emperor can’t get involved in politics, so the only way we can bring about real change in Japan is to have a new prime minister,” said Yamada, who was six years old when the current emperor’s reign began 30 years ago.

“But I still want the next emperor to do as much as he can to reach out to other countries, especially Japan’s neighbours.”