TOKYO (Reuters) - Crown Prince Naruhito, set to become Japan’s emperor on May 1, is known as an earnest, studious man who wooed and won his ex-diplomat wife, Crown Princess Masako, with a pledge to protect her.

FILE PHOTO: Japan's Crown Prince Naruhito and his wife, Crown Princess Masako, appear before well-wishers through bulletproof glass as they celebrate Emperor Akihito's 74th birthday at the Imperial Palace in Tokyo, Japan December 23, 2007. REUTERS/Issei Kato/File Photo

Naruhito, 59, will not only be the first Japanese emperor born after World War Two and the first to be raised solely by his parents, but also the first to graduate from a university and pursue advanced studies overseas.

He will assume the throne after his father, Emperor Akihito, abdicates on April 30, the first Japanese emperor to do so in nearly 200 years.

“When I think of what is coming up, I feel very solemn,” Naruhito said at his birthday news conference in February.

SELFIES WITH BYSTANDERS

Naruhito, the eldest of three children, was cared for by his mother, Empress Michiko, instead of being raised by wet nurses and tutors. She even sent him to school with homemade lunches as part of parental efforts to make the royal family seem closer to the people.

A student of medieval European river transport, Naruhito spent two years at Oxford University, a time he has described as some of the best years of his life.

Described by some as having a “playful” side, Naruhito posed for selfies with bystanders while visiting Denmark several years ago.

FAMILY DEVOTION

Naruhito defied palace officials to marry Masako Owada, now 55, after she caught his eye at a concert, prompting a years-long courtship during which she rejected his early proposals.

In late 2003, about a decade after their wedding, she largely disappeared from public view, the start of a long struggle with what palace officials termed an “adjustment disorder” brought on by the strains of palace life and demands she bear a male heir. In recent years her public appearances have increased.

At one point, Naruhito shocked the nation with his passionate defense of his wife, saying she had “totally exhausted herself” trying to adjust and that there had been moves to “negate her career and her personality.” His blunt remarks drew a rebuke from his younger brother and sorrowful remarks from the emperor.

Unique in becoming the first Japanese emperor in modern times to not to have a son, Naruhito has been devoted to his daughter Aiko, now 17, and has advocated for men becoming more hands-on fathers - still uncommon in conservative Japan.

WORTHY CAUSES

Naruhito, who espouses environmental causes, has taken part in international conferences on clean water and in 2015 made remarks at a U.N.-linked advisory board on water and sanitation. He has implied that he could work on climate change as well.

Masako has repeatedly said she is concerned about children in difficult situations, including those who are abused or live in poverty in Japan.

“When I think to the days ahead, I don’t know how useful I can be,” she said in remarks released on her birthday in 2018. “But after being by the sides of their majesties for all these years, and looking forward to their future guidance, I will make as much effort as possible to assist the crown prince and work for the happiness of the nation.”