It was all very polite.

Ambassadors, billionaires, a smattering of Biden family members and even one former president were all in attendance at the fifth state dinner President Biden and Jill Biden, the first lady, have held since taking office.

The gauzy celebration leaned heavily into Japanese fans, cherry blossoms and other tokens of the softer side of the U.S.-Japan relationship. The substance of the state visit of Prime Minister Fumio Kishida was focused on finding ways to counter China, but the style of the dinner was all about highlighting a capital city that owes its springtime resplendence, in large part, to the diplomatic overtures of the Japanese.

As the dinner got underway in the East Room, Mr. Biden toasted “to our alliance, to our friendship.” He kept things similarly light earlier in the evening when he greeted Mr. Kishida at the White House, replying, “Thank you,” to a question from a reporter about expectations that Iran would retaliate against Israel for its strike on an Iranian target in Syria.

Mr. Kishida also leaned into the idea of friendship.

“The Pacific Ocean does not separate Japan and the United States. Rather, it unites us,” Mr. Kishida said during his dinner toast, noting that President Kennedy once said the same thing 60 years ago. “I like this line. I use it so many times that my staff tried to delete it.”