King Charles III hailed Britain and Japan's "close friendship" at a lavish state banquet for Emperor Naruhito and Empress Masako at Buckingham Palace on Tuesday as the Japanese royals began a three-day state visit.
It is the first state visit to the UK by a Japanese head of state since 1998 and, unusually for such a trip, comes during a general election campaign.
Some typical political elements, such as a Downing Street visit, have been scrapped in line with neutrality rules but all the traditional pomp and pageantry has been maintained.
The emperor and empress, who arrived on Saturday and held informal weekend engagements, were formally greeted by Charles and Queen Camilla in central London to the sound of gun salutes and the two countries' national anthems.
They also met a host of other dignitaries, including Prime Minister Rishi Sunak, whose government has pushed for closer ties with Japan in recent years.
Naruhito, 64, and Charles, 75, inspected the guard of honour before the royals travelled the short distance to Buckingham Palace in a carriage procession for lunch.
The king, hosting his first state visit since it was revealed in February that he has cancer, later took his guests to a special exhibition of items from the Royal Collection relating to Japan.
He showed the emperor a delicately-painted scroll from 1855 from Queen Victoria's library showing the 17th-century coronation of Emperor Go-Mizunoo.
The current emperor could be heard saying "wonderful, wonderful" as he examined the objects on show.
The visiting royals next headed to lay a wreath at the Grave of the Unknown Warrior at Westminster Abbey, where they attended Queen Elizabeth II's state funeral in September 2022.
The day ended with a lavish state banquet where Charles paid tribute to "a close friendship" based on a shared understanding of international rules and institutions, forged "from the lessons of history, including its darkest years".
"Today, as we face a world in which these principles are ever more challenged, our shared values of freedom, democracy and the rule of law are more important than ever," he said.
Charles also wished a happy birthday to iconic Japanese animated character "Hello Kitty", a small white cat living in Britain that recently turned 50 years old.
Charles has made a limited return to public duties in recent months after doctors said they were "very encouraged" by his progress.
Princess Anne, the king's sister, had been due to attend but is recovering in hospital with a concussion and minor injuries after apparently being kicked by a horse.
Her husband, Timothy Laurence, told reporters on Tuesday that she was "recovering well".
The trip is the emperor's second official state visit since he acceded to the Chrysanthemum Throne in 2019, following a trip to Indonesia last year.
It was originally due to take place in 2020 and would have been the emperor's first overseas visit but it was delayed by the coronavirus pandemic.
Charles is hosting his third state visit since he became king following the death of his mother.
It was announced Tuesday he had approved an honours award for Nissan CEO Makoto Uchida -- making him an Honorary Commander of the Most Excellent Order of the British Empire (CBE) -- for services to UK-Japan business relations.
On Wednesday, Naruhito will visit The Francis Crick Institute, the UK's flagship biomedical research centre, before the Lord Mayor and City of London Corporation host a banquet for him that evening.
The emperor and empress will formally bid farewell to the king and queen at Buckingham Palace on Thursday morning before attending the "Japan: Myths to Manga" exhibition at London's V&A museum.
The emperor will later privately visit Windsor Castle to lay a wreath on the tomb of the late queen.
Elizabeth, whose 70-year reign began in 1952, hosted two Japanese state visits during her reign: Emperor Hirohito in 1971 and his eldest son Emperor Akihito -- Naruhito's father -- in 1998.
The Japanese couple head to Oxford, west of London, on Friday and will fly home from near there.
