Prime Minister John Key met his Japanese counterpart for half an hour last night in talks which focussed on Japan signing up to the Trans Pacific Partnership trade negotiations.
In April, Prime Minister Yoshihiko Noda formally declared Japan's interest in joining the TPP talks in November.
But he faces growing campaigns from supporters and opponents of Japan's proposed TPP participation.
New Zealand - a member of the TPP - wants a high quality and comprehensive free trade arrangement, including agricultural products, which in Japan are charged prohibitive duties.
The Government has been concerned the United States might concede ground to get the Japanese on board.
Mr Noda told Mr Key that Japan would join "under the right conditions".
Mr Key declined to reveal those conditions.
Trade analysts say New Zealand would make large gains if Japan and South Korea are in the TPP.
The New Zealand leader has been criticised for meeting Mr Noda, who is not expected to keep his job for much longer.
But Mr Key has been in Japan to mark 60 years since since the two countries established diplomatic relations and would normally be expected to meet the prime minister.
Among other topics, Mr Key raised New Zealand's longstanding opposition to whaling.
But both sides, stuck to their well-established positions.
Mr Key went to Japan from the Apec summit in Vladivostock, where he achieved one of his pre-conference objectives: getting to know the man whose election last March returned him as Russia's "new" president.
He not only scored a handshake, he got an apology from Vladimir Putin for his rudeness in keeping Mr Key waiting for two hours for their meeting last Saturday night.
It is understood that at one stage the Russians were considering cancelling the meeting as things were running so far behind schedule because of Mr Putin's tardiness.
That would have been a disaster for Mr Key personally and it would have sent a bad signal about Russia's attitude in the face of New Zealand's hopes of a "high quality" free trade deal with Moscow.
But after a frenzied round of cellphone calls between staffs, the meeting went ahead.
As for the free trade deal, Mr Putin's reissuing of an invitation to Mr Key to visit Russia next year increases the pressure on the negotiators to make compromises to get a result.