According to a former British ambassador to Tokyo, Japan views the United Kingdom leaving the European Union as an act of medium and long-term political and economical "self-harm" that will hurt relations with other nations around the globe.
Sir David Warren, who served as ambassador from 2008 to 2012, urged the need for plain speaking regarding the true, potentially devastating impact of Brexit, in an essay published by Chatham House.
"Privately, Japanese policy analysts are puzzled by British government rhetoric about the global opportunities that will follow the UK's leaving the EU," he writes.
"They observe that such opportunities have always been there: none depend on exit from the EU, whose Common Commercial Policy allows member states to maximize bilateral trade opportunities with other countries (as a glance at German trade statistics reveals).
"[The Japanese] question whether an independent UK will continue indefinitely to play a top-table role in the world."
Warren is an associate fellow in Chatham House's Asia programme and chairs the Japan Society, which is dedicated to UK-Japan ties.
"Japan sees power projection as heavily dependent on economic clout. Brexit is therefore regarded in Japan as an act of medium – and long-term economic, and therefore political, self-harm.
"Japan is the third-largest national economy in the world, with gross domestic product (GDP) of nearly $5 trillion; by comparison, Britain's GDP is a little more than half that. Japan sees the UK as a medium-sized world power effectively able to strengthen its economy by being part of the largest trading bloc for goods (and potentially services) in the world, and prepared to take a pragmatic approach to its sovereignty to reap those benefits.
"The strengthened economic heft as a result of EU membership in turn supports Britain's political role in the UN, the G7, NATO and elsewhere."
Warren goes on to say: "This is a time for plain speaking not rhetoric." However, he believes this the election of President Trump has created a "radically more uncertain international environment in which to do this".
He believes Trump represents an opportunity too however, "for the UK and Japan to work together to influence US thinking".
Last week Prime Minister Theresa May met with representatives of major Japanese companies such as Nissan and Toyota to assure them that the UK will continue to work with the EU following the country's departure from the union next year.
May said that a trade deal between Japan and the UK would be worked out based on the terms of the recent EU-Japan economic partnership agreement.