Emperor Naruhito, who ascended the throne on Wednesday, can claim a number of firsts as a member of the Japanese monarchy.
No emperor in the past had the experience of studying abroad, and he is also the first emperor not to be separated from his family and brought up largely by nannies.
The 59-year-old earlier signaled his intent to adapt to "the changing times," while also saying his years with his parents would serve as "major guideposts" for him as he performs his nonpolitical duties as the symbol of the state in the years ahead.
"I would like to pursue my duties as the symbol (of the state) by always being beside Japanese citizens, and sharing joy and sorrow with the people," he said at his last press conference as crown prince in February.
Emperor Naruhito was born on Feb. 23, 1960, as the elder son of former Emperor Akihito and his wife, former Empress Michiko, a year after their marriage. His now 84-year-old mother, formerly known as Michiko Shoda, was the first crown princess of commoner origin.
His name Naruhito, given by his grandfather Emperor Hirohito, posthumously known as Emperor Showa, consists of two Chinese characters taken from an ancient Chinese Confucian philosophy book and means "a man who acquires heavenly virtues."
Unlike his father, who grew up away from his parents in line with imperial family custom, Emperor Naruhito, his younger brother Crown Prince Fumihito, 53, and younger sister Sayako Kuroda, 50, who left the imperial household upon marriage to a commoner in 2005, were directly cared for by their parents as children.
The emperor entered the kindergarten of Gakushuin University in 1964 and attended the elementary, junior high and high schools of the university, which was established in the 19th century as a school for aristocrats.
"His majesty was gentle and always calm, and he naturally attracted people," recalled Akihiko Imai, a friend of the emperor's since junior high school.
In 1978, the emperor enrolled in the university's Faculty of Letters, where he majored in history. Before his graduation in 1982, he wrote a diploma thesis on medieval water transport in the Inland Sea area of western Japan.
After advancing to the graduate school of the private Japanese university in April 1982, he studied for two years from 1983 at the University of Oxford's Merton College, where he lived in a dormitory for the first time.
During his stay, he said he casually hit the pub, flooded a washing machine by putting in too many clothes and bought posters of American actresses Jane Fonda and Brooke Shields to decorate his room.
His research theme in Oxford was the history of transportation on the River Thames. He published a paper titled "The Thames as a Highway" in 1989 and was awarded an honorary degree of Doctor of Laws by the university in 1991.
This expertise led to him serving as honorary president of the U.N. Secretary-General's Advisory Board on Water and Sanitation between 2007 and 2015.
In January 1989, he became crown prince at the age of 28 after Emperor Akihito ascended to the Chrysanthemum Throne following Emperor Hirohito's death.
Having set himself the goal of finding a partner before turning 30, he got married to Masako Owada, a career diplomat who spent her childhood in Moscow and New York, at the age of 33 in June 1993.
The couple first met in October 1986 at a party to welcome visiting Spanish Princess Elena. Following the return of Empress Masako, 55, from the University of Oxford, where she studied between 1988 and 1990, the two met again in 1992 and he proposed marriage later that year.
"I will protect you with all my might for my entire life," the then-crown prince said in proposing to her.
Their wedding took place the following year, and the couple's only child, Princess Aiko, 17, was born on Dec. 1, 2001.
The emperor is known to have a number of hobbies, including mountain climbing, jogging, playing tennis and skiing. He plays viola and belonged to an orchestra during his time at Gakushuin University.
"Just like us, they have work and family, which give them power to lead their daily lives," said Imai, the emperor's friend, of the imperial couple.
The emperor had joined a variety of events and rituals in and outside the Imperial Palace, sometimes on behalf of former Emperor Akihito in recent years.
At a Gakushuin reunion in January 2018, the then-crown prince told friends who were chatting about reaching the retirement age of 60 in the near future, "In my case, I will be getting started," according to Yuko Matsuoka, who studied with him and was also at the gathering.
Matsuoka felt the emperor's "positive feelings about his enthronement" in the remark, she told Kyodo News.