Prime Minister Shinzo Abe will meet US President Donald Trump at the White House today, with their bilateral alliance under strain by a seeming chasm in their approach towards North Korea and trade.
North Korea will dominate their summit agenda, Japanese diplomats said. Despite Japan mulling over a challenge against the United States at the World Trade Organisation, trade issues will take a back seat until the Group of Seven (G-7) summit in Canada later this week.
Japan, which has long stressed that there is no daylight between Tokyo and Washington on policy coordination, angled for the meeting so that Mr Abe will have Mr Trump's ear just days before the highly anticipated US-North Korea summit in Singapore on Tuesday.
Japan, which favours a "maximum pressure" approach that has drawn pushback from both Koreas, has been anxious since Mr Trump said last week that he does not want to use the phrase any more.
While the White House has since stressed that there will be no relaxation of sanctions until the North denuclearises, Tokyo is still concerned that any easing of rhetoric will encourage sanctions evasion.
Given the potential for different interpretations of what denuclearisation means, Mr Abe will want to reiterate Japan's stance that there should be no easing of sanctions until "complete, verifiable, irreversible dismantlement" of the North's nuclear and ballistic missiles.
These include short-and intermediate-range ballistic missiles that have Japan in their crosshairs, and not just the intercontinental ballistic missiles potentially able to strike the US mainland.
"Japan's role is to remind Trump of the many possible traps in dealing with North Korea so that the coming summit will not end up just a political show," Keio University expert Yasushi Watanabe told The Straits Times, adding that recent messages from Washington might "sound a bit confusing" to Japan.
Mr Abe will also want to ensure that Mr Trump, at his meeting with Mr Kim Jong Un, will reject any assertion that the abduction of Japanese citizens - still a highly emotive issue for the Japanese - has been resolved fully.
Mr Abe has made it his top priority to ensure the return of Japanese citizens kidnapped by North Korea in the 1970s and 1980s to be trained as spies. Tokyo officially recognises 17 abductees, but Pyongyang puts the number at 13 - five were returned in 2002 and eight had died. North Korea says the other four never set foot in the country.
Kyodo news agency this week cited sources as saying that Mr Abe may ask Mr Trump to convey that Japan is open to negotiations with North Korea on normalising ties and extending economic cooperation so long as progress is made on the abduction issue.
That would be a positive step as Japan gropes for a resolution, experts said, as this means that Tokyo would have to ease up on its hawkish rhetoric.
"Sanctions are for operational applications, not for oral advertisement," Dr Katsuhisa Furukawa, a former United Nations expert monitoring sanctions against North Korea, told The Straits Times.
"As long as Japan sticks to its hardline position, I am concerned it would not be able to launch diplomatic efforts effectively to engage the North, which could open some chance for a breakthrough on the abduction issue."