TOKYO — President Trump has made some rocky telephone calls to other heads of state in his seven and a half months in office. But he can always count on one world leader for a good chat: Prime Minister Shinzo Abe of Japan.

Ever since the pair met in November at Trump Tower in New York just days after the presidential election, they have had a warm relationship that goes well beyond the typical partnership between two longstanding allies.

“It is very unusual,” said Mitoji Yabunaka, a longtime diplomat and former vice minister at Japan’s Foreign Ministry. “It did not happen that way in the past.”

Since Mr. Trump was inaugurated in January, he and Mr. Abe have met in person three times, golfed together once and talked by telephone 13 times, more than Mr. Abe spoke to President Barack Obama in his last four years in office. Over the past week alone, Mr. Abe and Mr. Trump have spoken by telephone four times.