Mr. Abe is “just trying to entertain President Trump and make his visit a political spectacle,” said Jiro Yamaguchi, a professor of political science at Hosei University. “But I must say Mr. Abe hasn’t achieved any results or any outcomes from these diplomatic activities. It is just a superficial political spectacle to conceal Mr. Abe’s failure in diplomacy.”

The prime minister has continued to heavily court Mr. Trump in hopes of sidestepping the rocky relations that the president is now facing with North Korea and China. But it is not clear such an approach will ultimately preserve an airtight bond. Although Mr. Abe shares some of Mr. Trump’s right-leaning philosophies, he is not the sort of strongman leader Mr. Trump often admires.

Still, with a culture known for its hospitality, putting on a lavish ceremonial show is one of the best cards that Japan has to play. On Sunday, Mr. Abe will host Mr. Trump at a basho, one of six annual grand tournaments in sumo, inviting the president to view one of the country’s most hallowed traditions. (There will still be an American twist: a Trump-themed trophy will go to the winner.) Plans for this event, a White House official told reporters this week, are “very much on.”

The cornerstone of the trip comes Monday, when the Trumps visit Emperor Naruhito, 59, who ascended to the Chrysanthemum Throne this month after the abdication of his 85-year-old father, Emperor Akihito. Mr. Trump will be the first visiting leader to meet the new emperor, and a state banquet will follow.

The Japanese are hailing this new era under Naruhito as “Reiwa” — which the government has translated as “beautiful harmony” — and Mr. Abe has made it clear that he wants this concept to define his relationship with Mr. Trump.

“Japan’s strategy from the get-go has been to really reach out to Trump personally,” Shihoko Goto, a senior associate for northeast Asia at the Wilson Center, said. “It’s precisely because they know the psychology of flattery that puts Japan into good graces with Trump.”

Mr. Abe has spent years studying what makes Mr. Trump tick. He convinced his reluctant friend to make the trip by emphasizing that a new emperor is about 100 times a bigger deal than the Super Bowl.