Tokyo: Japanese Emperor Naruhito is poised to officially proclaim his enthronement in a centuries-old ceremony attended by dignitaries, including heads of state and other royals, from more than 180 countries.
Naruhito, 59, and Empress Masako, a 55-year-old Harvard-educated former diplomat, took over in May in a brief, tradition-filled ceremony but Tuesday's "Sokui no Rei" is a more elaborate ritual in which he officially announces his change in status to the world.
Among the expected guests are Britain's Prince Charles, US Transport Secretary Elaine Chao and Australian Governor-General David Hurley. Myanmar civilian leader Aung San Suu Kyi is also expected to take part.
Naruhito is the first Japanese emperor born after World War II. He acceded to the throne when his father, Akihito, became the first Japanese monarch to abdicate in two centuries after worrying that advancing age might make it hard to perform official duties.
The celebratory mood for what has been proclaimed a special holiday has been tempered by Typhoon Hagibis, which tore through Japan 10 days ago. The typhoon killed at least 80 people and prompted the postponement of a planned celebratory parade.
Small groups of people waited at the Imperial Palace gate on Tuesday morning despite pouring rain and waved Japanese flags and cheered Naruhito as he entered by car, waving and smiling at them from an open window.
Naruhito began the day's ceremonies shortly afterwards by reporting his enthronement to his imperial ancestors at one of three shrines on the palace grounds, dressed in a black headdress and pure white robes with a long train borne by an attendant.
He was watched by other members of the imperial family, the women in long pastel dresses, and leading politicians, including Prime Minister Shinzo Abe.
For the main ceremony, Naruhito will wear a traditional robe and headdress, as his father did nearly three decades ago. It will start at 1pm local time at the Imperial Palace's Matsu no ma, or Hall of Pine, the most prestigious space in the palace where he officially succeeded his father "with a sense of solemnity" on May 1.
He will declare his enthronement from the "Takamikura" - a 6.5 metre high pavilion that weighs about 8 tonnes - with an ancient sword and a jewel, two of the so-called Three Sacred Treasures, placed beside him.
Together with a mirror called Yata-no-Kagami, which is kept at the Ise Grand Shrine, the holiest site in Japan's Shinto religion, the three treasures comprise the regalia that symbolises the legitimacy of the emperor.
Empress Masako will also take part in the ceremony, wearing heavy traditional robes and having her own throne.
Naruhito's address will be followed by a congratulatory speech by Abe, who will also lead three cheers for the new emperor to end the ceremony.
A court banquet will be held on Tuesday night, and Emperor Naruhito and Empress Masako will host a tea party for foreign royalty on Wednesday afternoon.
The celebratory parade has been postponed until November 10 while the government devotes its attention to coping with the aftermath of the typhoon.