The Surprising Reason Japan's Empress Wore a Face Mask During Horse-Drawn Carriage Ride with British Royals

Empress Masako of Japan slipped on an unexpected accessory on the first day of the state visit to the U.K. hosted by King Charles and Queen Camilla.

On June 25, the Japanese empress wore a face mask that matched her white ensemble for the horse-drawn carriage ride following the ceremonial welcome at Horse Guards Parade which kicked off the trip. Once the group stepped inside Buckingham Palace for lunch and to browse items from the Royal Collection relating to Japan, Empress Masako removed the accessory.

There was a practical reason for wearing the mask outdoors: Empress Masako is allergic to horses, according to royal reporter Rebecca English of the Daily Mail.

The Empress isn't the only one to allegedly be affected by the horses during royal pageantry. Prince Louis, 6, had a hilarious reaction, apparently to the animals' smell, when he briefly held his nose during a carriage ride at Trooping the Colour in June 2023.

Maskao, 60, was all smiles sans face mask when the day officially began as Prince William greeted her and her husband, Emperor Naruhito, at their hotel in London. The Prince of Wales, 41, stepped out solo for the key role highlighting his position as heir to the throne, a duty that his wife Kate Middleton has joined him for before. The Princess of Wales, 42, continues to remain outside of the spotlight while receiving cancer treatment. Although she appeared in public for the first time in nearly six months at Trooping the Colour on June 15, it didn't signal a return to work.

"She has been doing what’s right for her and recovering privately at home. She is dealing with it the best she can," a source close to the royal household tells PEOPLE exclusively in this week's cover story. 

Prince William accompanied the Emperor and Empress of Japan to Horse Guards Parade, where they greeted King Charles, 75, and Queen Camilla, 76, at the ceremonial welcome. 

Presentations were made, the Guard of Honour gave a Royal Salute and the Japanese national anthem was played. King Charles and Emperor Naruhito, 64, then inspected a Guard of Honour formed by the 1st Battalion Welsh Guards (of which Prince William serves as honorary colonel) before the carriage ride along The Mall in London, decorated with Japanese and Union Jack flags, to Buckingham Palace.

State visits are an important part of the British royal family’s diplomatic duties, organized to strengthen relationships with other nations around the world. The incoming state visit from Japan was announced in late April as part of King Charles' return to public duties amid his cancer treatment. 

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On June 4, Buckingham Palace confirmed that the state visit would be held from June 25 to June 27, ending speculation around the plans in light of British Prime Minister Rishi Sunak's May 22 announcement of a general election on July 4. At the time, the palace said the royals would postpone outings "which may appear to divert attention or distract from the election campaign." Members of the British royal family are constitutionally non-political and usually leave the public space during campaigns to focus public attention on the election and the issues it presents.

The Emperor and Empress of Japan arrived in England on June 22 for a series of private engagements before the state visit officially kicked off on June 25.

The British royals will reconvene with the Emperor and Empress for a state banquet at the palace tonight.

The glam occasion might mean a tiara moment for Queen Camilla, though Princess Anne is not expected to attend after being hospitalized following an accident at her country home on June 23.