Iranian Foreign Minister Mohammad Javad Zarif's three-day visit to Japan was apparently arranged hastily. It was announced on Wednesday, the day he arrived.
The visit seems to be part of Iran's efforts to drum up support from the international community in the face of intensifying pressure from the United States.
Japan has friendly ties with Iran. Japan is also an ally of the United States, and Prime Minister Shinzo Abe maintains good relations with US President Donald Trump. That may put Japan in a position to serve as a go-between for Iran and the United States, as the two countries do not have diplomatic ties.
Japan will also host the G20 summit in Osaka in June, which Trump is due to attend.
Iran may be hoping that Japan will use that opportunity to help improve Tehran's communications with the United States.
Zarif has accused US National Security Advisor John Bolton, Israeli Prime Minister Benjamin Netanyahu, Saudi Arabian Crown Prince Mohammed bin Salman and UAE Crown Prince Mohammed bin Zayed of trying to force regime change in Iran through attempts to incite a military clash. Zarif refers to them as "the B team" as they all have a B in their names.
In the face of mounting international pressure, Zarif is stepping up diplomatic efforts to try to defuse tensions with the United States. Before travelling to Japan, Zarif visited Russia and India. The two countries also have friendly ties with Iran.