TOKYO — Under a blazing hot sun at Japan’s Imperial Palace, President Donald Trump on Monday became the first world leader to meet the new emperor of Japan.

The president, who is on a four-day state visit, was the center of attention at a grand outdoor welcome ceremony where he took a solo walk down red carpets, reviewing Japanese troops as the guest of honor. The pomp and pageantry then gave way to meetings with Japanese Prime Minister Shinzo Abe about trade and other world issues.

Trump’s “state call” opened with handshakes and greetings from Naruhito, who ascended to the throne on May 1, and his wife, Empress Masako.

As he approached the emperor, Trump said, “How are you? Thank you very much.” The first lady told the empress, “Nice to meet you.”

After exchanging pleasantries inside the palace, the couples emerged and walked to a raised platform as the national anthems of both countries were played.

Trump showed little emotion, but waved near schoolchildren feverishly waving U.S. and Japanese flags. Some of the children suffered from the heat and were later seen siting with cups of water and cool compresses on their foreheads.

At the White House last week, Trump noted the significance of his meeting with the emperor. Naruhito took the throne after his father stepped down, the first abdication in Japan’s royal family in about two centuries.

“It’s a very big thing going on with the emperor. It’s something that hasn’t happened in over 200 years,” Trump said. “I am the guest, meaning the United States is the guest.”

Trump stressed that Abe “very specifically” said Trump is the guest of honor.

“With all the countries of the world, I’m the guest of honor at the biggest event that they’ve had in over 200 years,” Trump said.

It’s not the emperor who chose Trump as his first state guest. It was Abe, who is seen by some as using the invitation to meet Naruhito to curry favor with Trump who is threatening to impose potentially devastating tariffs on Japan’s auto industry, among other tensions in the relationship..

After leaving the Imperial Palace, Trump went to the Akasaka Palace, the Japanese state guest house with lush manicured grounds, for meetings, a working lunch and joint news conference with Abe. The president also will be the guest of honor at an imperial banquet at the palace hosted by the emperor.