Crown Prince Fumihito, who was formally declared as first in line to the Chrysanthemum Throne on Sunday, is known for publicly speaking his mind about the role of the imperial family in modern-day Japan.
The 54-year-old younger brother of Emperor Naruhito, 60, has occasionally expressed his view that the imperial family needs to adapt to the times while saying he will work alongside and support his brother, who ascended to the throne in May last year.
On the occasion of his 52nd birthday in 2017, he said, "Of course, I think what (people) seek from us changes depending on the times. I think we need to always keep that in my mind."
He made the comments after a law was enacted to allow former Emperor Akihito, 86, the father of the emperor and crown prince, to abdicate. The former emperor stepped down in April last year following a 30-year reign, becoming the first Japanese monarch to relinquish the throne in around 200 years.
The crown prince holds positions at a number of organizations, including the presidency of the Japanese Association of Zoos and Aquariums, and as the honorary president of the World Wide Fund for Nature Japan. He also served as the honorary head of last year's Rugby World Cup in Japan.
Born on Nov. 30, 1965, he is the youngest son of former Emperor Akihito and former Empress Michiko, 86, and was called Prince Aya when he was young. The couple has a daughter, Sayako Kuroda, who left the imperial household upon marriage to a commoner in 2005.
The crown prince attended Gakushuin Primary School, as did his brother and many other imperial family members, and advanced to its junior high school and senior high school before entering Gakushuin University's Faculty of Law, Department of Political Studies.
After graduating in 1988, he went to Britain to study at the University of Oxford's St. John's College in the Graduate School of Zoology, returning to Japan in 1990. He received his doctorate of philosophy from the Graduate University for Advanced Studies in 1996.
The crown prince has loved animals since childhood and has conducted research into giant catfish and the domestication of chickens, and has served as a guest professor at Tokyo University of Agriculture.
He has received honorary doctorates from at least 10 Thai universities in recognition of his contributions to the promotion of fisheries and poultry science in Thailand.
In June 1990, he married Kiko Kawashima, who also studied at Gakushuin University, which marked the start of the Akishino family. They celebrated their 30th wedding anniversary this year.
The couple's first daughter Princess Mako, 29, was born in October 1991, and their second, Princess Kako, 25, was born in December 1994. In September 2006, Prince Hisahito was born, becoming the imperial family's first boy and first heir to the Chrysanthemum Throne born in 41 years.
Prince Hisahito, 14, currently a student at Ochanomizu University Junior High School, is second in line to the throne.
The crown prince and his family have attracted nationwide attention following the postponement of the planned marriage between Princess Mako and her university boyfriend Kei Komuro, 29.
The two announced their planned engagement in September 2017 and said their wedding would take place in November 2018.
The Imperial Household Agency, however, said in February that year the couple was postponing the wedding until 2020, following a string of reports that Komuro's mother was involved in a dispute with her former fiance over money, including her son's educational costs, which the man shouldered.
The crown prince has said the engagement ritual cannot be held unless the couple gains support and understanding from the public, while urging the Komuros to resolve the issue. Last year, he said the princess must update the public on the matter, but no statement has been made so far.