Mr. Trump of course fell for it, hook, line and sinker.
"So, I was seated next to the wife of Prime Minister Abe, who I think is a terrific guy, and she's a terrific woman, but doesn't speak English," Mr. Trump told New York Times reporter Maggie Haberman.
"Like, nothing, right? Like zero?" she asked him.
"Like, not even 'hello,' " replied Mr. Trump.
"But I enjoyed the evening with her, and she's really a lovely woman, and… the whole thing was good," said Mr. Trump, for once trying hard not to create a diplomatic incident.
The #G20Summit was a wonderful success and carried out beautifully by Chancellor Angela Merkel. Thank you!— Donald J. Trump (@realDonaldTrump) July 8, 2017
Imagine how hurt the "leader of the free world" would have been when he read that the wife of Prime Minister Shinzo Abe speaks perfect English, with only a slight accent.
She has been seen chatting away happily in English with Michelle Obama and with Sophie Gregoire Trudeau, wife of Canadian Prime Minister Justin.
Back in 2007, she happily chatted away in English with Boston Red Sox pitcher Daisuke Matsuzaka at a White House reception hosted by then President George W. Bush and his wife Laura.
She even chatted with Melania Trump earlier this year at the Mar-a-Lago resort in Florida, when their husbands were playing golf.
So it must be something personal.
When an opera performance at the G20 summit ended, Mrs. Abe sat in stony silence next to Mr. Trump for around an hour and a half during dinner rather than converse with him.
Mrs. Abe, who is from a wealthy Japanese family, used to work as a DJ in her home town of Shimonoseki.
She is a supporter of the LGBT community and joined the gay pride community in Tokyo in 2014.
"I don't think I have any special talents, but I am able to make connections with people. I'm one of the few people in this country who can talk to a wide range of people, from the Emperor to the homeless," she said during an interview last year.
Mrs. Abe's husband is the leader of the Liberal Democratic Party which, despite its name, is a conservative party which has ruled Japan almost without interruption since 1945.
Her behavior may have been influenced by Mr. Trump's famously crude attitude towards women, which was underlined recently by creepy remarks he made about French President Emmanuel Macron's wife Brigitte.
"You're in such good shape. She's in such good physical shape. Beautiful," said Mr. Trump.
Mrs. Macron is 64, a quarter of a century older than her husband.