Emperor Naruhito of Japan inspects the Guard of Honour formed of the 1st Battalion Welsh Guards during a ceremonial welcome for him and Empress Masako on the occasion of their state visit to Britain, at Horse Guards Parade, London, Tuesday, June 25, 2024. (Chris Jackson/Pool Photo via AP)
Japans Emperor Naruhito, left, and Britain's King Charles III walk back from inspecting the honour guard on Horse Guards parade during the ceremonial welcome for start of the State Visit to Britain by the Emperor and Empress in London, Tuesday, June 25, 2024. (AP Photo/Kin Cheung, Pool)
Japans Emperor Naruhito inspects the honour guard on Horse Guards parade during the ceremonial welcome for start of the State Visit to Britain by the Japanese Emperor and Empress, in London, Tuesday, June 25, 2024. (AP Photo/Kin Cheung, Pool)
Britain's King Charles III, right with Japans Emperor Naruhito, Empress Masako, and Queen Camilla pose for the cameras ahead of the State Banquet during the State Visit to Britain of the Japanese Emperor and Empress in London, Tuesday, June 25, 2024. (AP Photo/Kirsty Wigglesworth, Pool)
Britain's King Charles III, right, and Emperor Naruhito during the ceremonial welcome at Horse Guards Parade, London, for the state visit to the UK of the Emperor and his wife Empress Masako, Tuesday June 25, 2024. (Jeff Moore/PA via AP)
From left, Japan's Empress Masako, Britain's Queen Camilla, Britain's King Charles III and Japan's Emperor Naruhito pose for a family photo at the ceremonial welcome for their state visit to Britain, at Horse Guards Parade, London, Tuesday, June 25, 2024.(Chris Jackson/Pool Photo via AP)
The finishing touches are applied to the tables in the Ballroom of Buckingham Palace, before the State Banquet for the State Visit by Emperor Naruhito and his wife, Empress Masako of Japan, in London, Tuesday June 25, 2024. (Aaron Chown/PA via AP)
Britain's King Charles III and Japan's Emperor Naruhito ride a carriage during a welcome ceremony for Naruhito's state visit to Britain, at Horse Guards Parade, London, Tuesday, June 25, 2024. (Eddie Mulholland/Pool Photo via AP)
Britain's Queen Camilla, left,and Japan's Empress Masako, ride in an open carriage during the ceremonial welcome for the State Visit to Britain of the Japanese Emperor and Empress, in London, Tuesday, June 25, 2024. (Jonathan Brady, Pool Photo via AP)
Japans Emperor Naruhito inspects the honour guard on Horse Guards parade during the ceremonial welcome for start of the State Visit to Britain by the Japanese Emperor and Empress, in London, Tuesday, June 25, 2024. (AP Photo/Kin Cheung, Pool)
Guests attend the State Banquet for Emperor Naruhito and Empress Masako of Japan in London, Tuesday, June 25, 2024, during the State Visit of the Japanese Emperor and Empress to Britain. (Jordan Pettitt/Pool via AP)
Britain's King Charles III walks with Japan's Emperor Naruhito, followed by Britain's Queen Camilla and Japan's Empress Masako as they view a display of Japanese items from the Royal Collection, in the Picture Gallery at Buckingham Palace in London, Tuesday, June 25, 2024, on the first day of their three-day State Visit to Britain. The Japanese royal couple arrived in Britain for a three-day state visit hosted by King Charles III. (Henry Nicholls/pool photo via AP)
Japan's Emperor Naruhito, accompanied by Britain's King Charles, rides in a carriage on the day of a state visit, in London, Britain, Tuesday, June 25, 2024. (Isabel Infantes/Pool photo via AP)
Britain's King Charles III, left, and Emperor Naruhito of Japan arrive at Buckingham Palace during the ceremonial welcome for the State Visit to Britain of the Japanese Emperor and Empress, in London, Tuesday, June 25, 2024. (Jonathan Brady, Pool Photo via AP)
Britain's King Charles III and Japans Emperor Naruhito ride in an open carriage as they ride down the Mall scorted by mounted troops during the ceremonial welcome for the State Visit to Britain by the Japanese Emperor and Empress, in London, Tuesday, June 25, 2024. (AP Photo/Alberto Pezzali)
The finishing touches are applied to the tables in the Ballroom of Buckingham Palace, before the State Banquet for the State Visit by Emperor Naruhito and his wife, Empress Masako of Japan, in London, Tuesday June 25, 2024. (Aaron Chown/PA via AP)
Britain's King Charles III, right, and Japan's Emperor Naruhito toast glasses at the State Banquet in London, Tuesday, June 25, 2024, during the State Visit of the Japanese Emperor and Empress to Britain. (Jordan Pettitt/Pool via AP)
Japan's Empress Masako, arrives by car to attend the ceremonial start of the State Visit to Britain by the Japanese Emperor and Empress in London, Tuesday, June 25, 2024, of a state visit. (AP Photo/Kin Cheung, Pool)
Britain's King Charles III, Emperor Naruhito, left, Empress Masako and Queen Camilla, right, make their way along the East Gallery to attend the State Banquet in London, Tuesday, June 25, 2024, during the State Visit of the Japanese Emperor and Empress to Britain. (Aaron Chown/Pool via AP)
Japans Emperor Naruhito arrives by car for the ceremonial welcome by King Charles III at the start of the State Visit to Britain by the Japanese Emperor and Empress, in London, Tuesday, June 25, 2024. (AP Photo/Kin Cheung, Pool)
Britain's King Charles III, Japan's Emperor Naruhito, Britain's Queen Camilla and Japan's Empress Masako view a display of Japanese items from the Royal Collection, in the Picture Gallery at Buckingham Palace in London, Tuesday, June 25, 2024, on the first day of their three-day State Visit to Britain. The Japanese royal couple arrived in Britain for a three-day state visit hosted by King Charles III. (Henry Nicholls/pool photo via AP)
Britain's Prince William, right, sits by Hirofumi Nakasone, the Japan party's head of the official suite, as they arrive at Buckingham Palace during the ceremonial welcome for the State Visit to Britain of the Japanese Emperor and Empress, in London, Tuesday, June 25, 2024. (Jonathan Brady, Pool Photo via AP)