The date was announced after a meeting today of the Japanese Imperial Household Agency. 

Eighty-three-year-old Akhito will be succeeded by 57-year-old Crown Prince Naruhito, which will mean a third generation of the Japanese Royal Family will open an Olympic Games when he makes the traditional proclamation at Tokyo 2020.

"It gives me a profound sense of awe that we have taken a significant step towards the throne's accession," said Japan's Prime Minister Shinzō Abe.

The decision will be discussed by the Japanese cabinet next week and a formal confirmation of the date will be made by an Government ordinance, possibly within a week.

Akihito acceded to what is known as the "Chrysanthemum" throne on the death of his father in 1989. 

He first made his intention to stand down public in August of last year after expressing concern about his failing health.

"When the Emperor has ill health and his condition becomes serious, I am concerned that, as we have seen in the past, society comes to a standstill," he said.

In June, the Japanese Parliament passed a special bill which enabled Akihito to abdicate.

Naruhito was a patron of the Japanese Olympic Committee and was on hand to witness speed skater Hiroyasu Shimizu win gold at the 1998 Winter Games in Nagano.

He also has some practical experience of involvement at major Games.

In February he made the official declaration at the Asian Winter Games in Sapporo and he also opened the 1998 Paralympics in Nagano.

He also opened the 1991 Winter Universiade in Sapporo.

In 2020, speaking in Japanese, he will deliver the words set down in the Olympic Charter - "I declare open the Games of Tokyo celebrating the 31st Olympiad of the Modern Era".

He is also expected to open the International Olympic Committee Session in Tokyo which will immediately precede the Games.

Emperor Akihito previously opened the Nagano 1998 Games and was set to emulate his own father, Emperor Hirohito, at a home Summer Games in Tokyo.

Former IOC President Avery Brundage used a special form of words to invite Hirohito to open the 1964 Tokyo Games. 

Hirohito also opened the Winter Games in Sapporo 1972 and remains as the only monarch to do so for both a Summer and Winter Olympics. 

At both Games Aikihito and his wife were also keen spectators.

It seems certain that Prince Naruhito will follow suit in 2020.