US President Barack Obama talks with Japan's Emperor Akihito and Empress Michiko as they walk in the Imperial Palace in Tokyo on Thursday. Toru Hanai / Reuters

Japanese Prime Minister Shinzo Abe may have hoped to demonstrate his personal ties with US President Barack Obama during the US leader's state visit to Tokyo, but if how they addressed each other in public was any gauge, the effort fell short.

Ronald Reagan and then- Japanese prime minister Yasuhiro Nakasone set the gold standard for chummy relations between leaders of the two allies back in the 1980s, when they famously called each other by the nicknames "Ron" and "Yasu".

George W. Bush and Junichiro Koizumi also bonded during Koizumi's term as Japanese leader from 2001 to 2006, playing ball, eating barbecue at Bush's Texas ranch and visiting Elvis Presley's Graceland mansion, where Koizumi crooned Elvis tunes.

Abe, perhaps keen to dispel talk that he and Obama - who is often described as cerebral and businesslike - didn't click, spoke warmly of their Wednesday-evening casual sushi dinner.

"He told me the sushi we had last night was the best he'd had in his life. We spoke for an hour and a half about the issues between Japan and the US, and about global issues," Abe said at a joint news conference after their summit on Thursday.

Obama, for his part, thanked Abe for Japan's warm welcome and some "outstanding sushi and sake".

But Abe's repeated use of Obama's first name during the media event - he called him "Barack" at least six times - went mostly unrequited, with the president referring to the Japanese prime minister as "Shinzo" only a couple of times.

"Japanese love the idea of the two leaders being on a first-name basis," said one political scientist. "Obama not saying it enough - there are people who will read something into it."

Reuters