ITV News Political Correspondent Carl Dinnen is travelling with the Prime Minister as she heads to Japan for trade talks.
The Prime Minister is on her way to Japan with London and Tokyo hoping for different things out of the trip; Tokyo wants reassurance, London wants to get going on a trade deal.
But the Japanese aren't ready to offer substantial progress on a trade deal because they're still working on a bigger one with, guess who, the European Union.
What Tokyo wants is reassurance about the future for the 1,000 Japanese businesses in the UK, some of whom are already worried enough to be moving their operations to countries where they know they can keep trading freely with the EU.
And with Brexit negotiations yet to even reach the future trading relationship, it's hard to see how Mrs May can offer the reassurance Prime Minister Shinzo Abe will be seeking.
It's unlikely either side will get what they really want out of this trip.