Emperor Naruhito is ready to ascend the Chrysanthemum Throne. What can Japan expect from its new ruler?

He became the first Japanese royal to study abroad, spending two years at Oxford University in the United Kingdom, writing a thesis on medieval mercantilism on the River Thames, before returning to Tokyo and his alma mater, Gakushuin University, for doctoral studies.

The easygoing personality and sense of humor of the anglophile Naruhito shines through in his book "The Thames and I: A Memoir of Two Years at Oxford."

Now he must emerge from his father's shadow and establish himself as a modern leader.

Naruhito, who has already assumed some of his father's duties, will usher in the "Reiwa" era -- whose name includes the character for "harmony" -- when he ascends the throne on May 1.

"It is his reign name to shape through his actions and gestures," says Kingston, adding that Naruhito's challenge in defining his era will be to avoid getting "co-opted by Japan's right-leaning politicians."

The Chrysanthemum Throne is the oldest hereditary monarchy in the world, and records show the royal male line to be unbroken for 14 centuries. Naruhito himself is a direct descendant of Japan's first emperor Jimmu, circa 660 BC.

The only child of Naruhito and his wife Masako is a daughter, Aiko, and women are barred from the throne. This means that the new emperor's brother, Akishino, will become first in line to the throne while Akishino's 12-year-old son Hisahito -- the only male member of that generation of Japanese royals -- will be second.

Other imperial traditions have been loosened, especially in regard to marriage.

Akihito became the first emperor to marry a commoner, after meeting Michiko in 1957 during a tennis match in the scenic mountain town of Karuizawa.

The couple also broke with tradition to play an active part in raising their four children, including the future emperor.

Naruhito followed suit in 1993 by marrying career diplomat Masako Owada, despite her reservations at becoming part of the rigorously traditional and hidebound Imperial Household.

Masako, under tremendous pressure to produce a male heir to continue the unbroken line, suffered a miscarriage in 1999 before giving birth to Aiko two years later.

Imperial Household doctors diagnosed her as suffering from a "adjustment disorder" caused by stress, which can cause depression.

Naruhito has been deeply protective of his wife. Even when they were courting, he promised to shield her from the scrutiny and rigors of imperial life.

The new emperor is "something of a maverick," Kingston says, citing Naruhito's controversial remarks in 2004, when he suggested that Imperial Household bureaucrats were to blame for his wife's condition due to "their obsessive focus on her producing a male heir."

Jeremy Yellen, an assistant professor in the Department of Japanese Studies at the Chinese University of Hong Kong, says that in the new era he expects Naruhito "will continue to be very protective of his wife, Princess Masako, and his family."

Until Emperor Hirohito renounced his divine status in the wake of Japan's Second World War defeat and subsequent occupation by the United States military, Japanese emperors were seen as demigods.

Hirohito's son Akihito, in contrast, denounced militarism and opposed revisionist accounts of the war years.

Naruhito has indicated that he will continue his father's legacy, Yellen says.

"I find it highly likely that he will follow many of the precedents that made his father such a success with the media. Although the issue may not be as important to him as it was to his father, I believe that he will continue Emperor Akihito's rejection of revisionist views of Japan's wartime past."

At birthday press conferences in recent years Naruhito has made it clear that he shares his father's views about Japan's war responsibility and his unwavering commitment to pacifism.

"I myself did not experience the war," he said on his 55th birthday in 2015. "But I think that it is important today, when memories of the war are fading, to look back humbly on the past and correctly pass on the tragic experiences and history Japan pursued from the generation which experienced the war to those without direct knowledge."

However, Kingston says the anti-war message may not resonate as strongly with the current generation, who have no memories of the war or of post-war privations.

Instead, many look at the changing geopolitics of the region, particularly the rise of China.

"Millennials... see Asia as a threatening and often hostile neighborhood," he says.

Naruhito, whose birth name means "a man who will acquire heavenly virtues," seems likely to keep pushing for societal change. He has a particular interest in clean water and water conservation, and Kingston says this is likely his best chance of defining himself independently of his beloved 85-year-old father, who took over the throne in 1989.

"In order to emerge from his father's long shadow, climate change might become Naruhito's signature cause, drawing on his longstanding interest in water-related environmental issues to champion disaster resilience and sustainable development."

Naruhito has "already apprenticed extensively in the role of consoler-in-chief," says Kingston, paying frequent visits to the Tohoku region which was devastated by the 2011 tsunami.

He also "lends support to various causes supportive of the vulnerable and marginalized," Kingston says.