“Our governments are working together to provide a stable world for future generations,” said Charles, flanked by Queen Camilla on one side and Naruhito on the other.
“Supporting all these shared endeavors are the enduring ties between our people that transcend geography — and that does not just mean how much we enjoy tea and talking about the weather.”
The emperor’s trip, postponed from 2020 due to the COVID-19 pandemic, seeks to deepen the military, cultural and scientific links between the two countries.
Naruhito paid tribute to the late Queen Elizabeth, who was on the throne when the invitation was first issued, highlighted Charles’ work on environmental projects and spoke of the strength of diplomatic ties.
“The multi-layered collaboration and exchange between our two countries is accelerating in various areas, including politics and diplomacy, the economy, culture and the arts, science and technology, as well as education,” he said. “Our bilateral relations have never been more robust.”
Charles’ son and heir to the throne, Prince William, had earlier traveled to the hotel where the 64-year-old emperor and Empress Masako were staying, before the trio arrived for a ceremonial welcome at Horse Guards Parade on Tuesday.
The two heads of state — Charles wearing a top hat — then inspected the Guard of Honor as the rows of soldiers in their traditional scarlet uniforms and black bearskin hats stood in the summer heat.
They then traveled to Buckingham Palace in a gold-edged horse-driven carriage.
The visit is taking place in the run-up to an election in Britain on July 4, meaning that some of the usual political elements will be missing.
There will be no meeting at Downing Street between the emperor and British Prime Minister Rishi Sunak, although Sunak and opposition leader Kier Starmer both attended the banquet.
The visit comes at a difficult time for the British monarchy, after Charles, 75, was diagnosed with cancer earlier this year, and as William’s wife, Catherine, undergoes preventative chemotherapy treatment for cancer.
In another setback, Princess Anne, Charles’ younger sister, suffered a head injury on Sunday after an incident believed to have involved a horse. While she is expected to make a full recovery, she pulled out of attending the state banquet.
Naruhito came to London in 2022 to attend Queen Elizabeth’s funeral and is fond of Britain, having studied here in the early 1980s.
He has spoken of the kindness the British royals showed him at that time, including a visit to the royal family at Balmoral Castle in Scotland, where Charles took him fly fishing.
The pair took lunch at Buckingham Palace and then viewed Japanese-related items from the royal collection before a tour of Westminster Abbey.