Mobara, Japan — President Trump presented a special Trump trophy to the winner of a sumo tournament in Tokyo on Sunday as he got a taste of one of Japan's most treasured cultural institutions.

The honor given to Mr. Trump was part of a charm offensive Japanese Prime Minister Shinzo Abe continued Sunday as he courted the president with three things close to his heart: wrestling matches, cheeseburgers and golf.

Call it sumo diplomacy.

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The president, first lady Melania Trump, Abe and his wife, Akie, joined an estimated 11,500 fans who packed Ryogoku Kokugikan Stadium to watch oversized, muscular men battling in loincloths.

At the end, Mr. Trump stepped into the ring and presented the eagle-topped "President's Cup" to champion wrestler Asanoyama, making him the first American president to participate. Shoes aren't permitted in the sumo ring, but Mr. Trump wore dark-colored slippers.

President Trump, first lady Melania Trump, Japanese Prime Minister Shinzo Abe and wife Akie Abe watch the Summer Grand Sumo Tournament at Ryogoku Kokugikan Sumo Hall in Tokyo, Japan, on May 26, 2019. JONATHAN ERNST / REUTERS

"That was something to see these great athletes," Mr. Trump said before dinner at a Hibachi restaurant.

Mr. Trump's four-day state visit to Japan is designed to demonstrate the strength of the bond between the nations. The president received a warm welcome as he arrived at Mobara Country Club, south of Tokyo, for a steamy morning round of golf with the Japanese leader. It was their fifth golf outing.

Abe is pulling out all the stops as he seeks to placate Mr. Trump amid growing U.S.-Japan trade tensions and the threat of auto tariffs. Japan is also contending with the continued threat of North Korea and Mr. Trump's apparent dismissal of Pyongyang's recent tests of short-range missiles that could reach Japan.

But minus several antagonistic tweets, Sunday was all about bromance and keeping Mr. Trump happy.

First it was the golf course, where Mr. Trump and Abe played 16 holes, joined by Japanese professional golfer Isao Aoki. Aoki, who is famous for his putting technique, was expected to present Mr. Trump with a putter he designed.

President Trump talks with Japanese Prime Minister Shinzo Abe as they play golf at Mobara Country Club in Japan, in this photo released by Japan's Cabinet Public Relations Office via Kyodo May 26, 2019. KYODO / REUTERS

On the lunch menu: Double cheeseburgers made with U.S. beef.

Next, Abe introduced Mr. Trump to Japan's ancient sport of sumo wrestling — something Mr. Trump has said he said he finds "fascinating."

The president was welcomed to the stadium with loud applause and sat ringside at the match in a low-back, breaking the custom of sitting cross-legged on a mat. Once it was done, Mr. Trump climbed on stage to present his cup to wrestler Asanoyama, who clinched the tournament win on Saturday.

Mr. Trump read from a scroll, praising Asanoyama's "outstanding achievement" and then hoisted the hefty cup, which the White House said stands 54 inches tall and weighs 60 to 70 pounds, into Asanoyama's arms with the help of an official.

Asanoyama was presented with a trophy by Abe and an emperor's trophy as well.

President Trump presents the President's Cup to wrestler Asanoyama, the winner of the Summer Grand Sumo Tournament at Ryogoku Kokugikan Sumo Hall in Tokyo, Japan, on May 26, 2019. JONATHAN ERNST / REUTERS

The president's attendance at the annual summer sumo tournament in Tokyo might have recalled memories of time he spent promoting the World Wrestling Federation. Mr. Trump sponsored major events, appeared in bits and was inducted into the World Wrestling Entertainment Hall of Fame in 2013.

On Monday, Mr. Trump will receive another honor when he becomes the first foreign leader to meet with Japan's new emperor, Naruhito, since he ascended to the throne on May 1. Mr. Trump and Abe will also meet in a more formal setting and participate in a joint news conference. In the evening, Mr. Trump will be guest of honor at a banquet hosted by the emperor at Japan's Imperial Palace.

"We've had a great time, a great stay, and tomorrow is really the big event, a very important event in the history of Japan," Mr. Trump said. "It's over 200 years since something like this has happened so it's a great honor to be representing the United States."

The Abe-Trump bromance began even before Mr. Trump took office when Abe rushed to New York to greet the president-elect at Trump Tower. Japan is deeply dependent on the U.S. for security and Abe has tried to encourage Trump to maintain international agreements and keep pressure on North Korea.

Golf, in particular, has been a bonding activity for the leaders, who both love the game.

"We were able to exchange our views frankly in a cozy atmosphere. It was wonderful," Abe told reporters as he returned to his official residence mid-day. He tweeted a selfie photo of him and Mr. Trump, smiling widely on the greens.

Mr. Trump tweeted that he'd had "Great fun and meeting with Prime Minister @AbeShinzo," but also continued to stew about domestic politics, claiming that, "Numerous Japanese officials told me that the Democrats would rather see the United States fail than see me or the Republican Party succeed - Death Wish!"

There has long been a tradition of American presidents and candidates holding their tongues about rivals while on foreign soil — but Mr. Trump is not one to abide by such norms.

Earlier, Mr. Trump had gone after one of his potential Democratic rivals, former Vice President Joe Biden, saying he'd smiled when North Korean leader Kim Jong Un "called Swampman Joe Biden a low IQ individual, & worse."

He also downplayed North Korea's recent series of short-range missile tests. He tweeted that the tests weren't a concern for him — even though they most certainly are for Japan, due to the country's proximity to the North.

"North Korea fired off some small weapons, which disturbed some of my people, and others, but not me," Mr. Trump wrote in a message that appeared to undermine his national security adviser, John Bolton, who told reporters Saturday the tests violated U.N. Security Council resolutions.

The president also sought to manage expectations that he and Abe will make significant headway on trade issues when they hold more formal talks on Monday. Mr. Trump has been seeking a bilateral trade agreement with Tokyo since he pulled the U.S. out of the multinational Trans-Pacific Partnership trade agreement two years ago, though analysts expect no breakthroughs during Mr. Trump's visit.

"Great progress being made in our Trade Negotiations with Japan. Agriculture and beef heavily in play. Much will wait until after their July elections where I anticipate big numbers!" he wrote, referring to Japan's upcoming parliamentary elections.

The Trump administration has been threatening Japan with new tariffs on imports of autos and auto parts on national security grounds. Mr. Trump has suggested he will impose tariffs if the U.S. can't wrest concessions from Japan and the European Union. In April, Japan's trade surplus surged almost 18% to 723 billion yen ($6.6 billion).