Nippon Export and Investment Insurance (NEXI)
They do Trade Insurance.


Trade Insurance covers risks that arise from trade transactions
and overseas investment which are not in general covered by
marine insurance.
This system developed at an early stage in the Western
countries including United Kingdom, in countries which are
highly dependent on trade. It is also called
Export Credit Insurance or Export Credit Guarantee.
(from the website)


If your shipper (supplier in Japan) is hesitant to send the goods
unless it’s cash in advance, suggest to them NEXI with above link.