Related question that brings something up. Japan was importing most of its oil from the USA, until the oil embargo was imposed in summer 1941. Before this embargo, how did Japan pay for this oil? What did they trade for it? Gold or silver?
Before 1930, Japan had a "considerable (see quote below if link is broken)" trade surplus with the US, much of this stemming from exports of silk. Japan also had a substantial trade surplus with China (from cotton textiles). In the 1930s,
Japan exported textiles and miscellaneous articles to Southeast Asia and exported less to the United States and China, with both of which Japan had had a considerable trade surplus prior to 1930. In the 1930s, Japan imported raw cotton, petroleum and so on from the US, and imported less from India, with which Japan had had a considerable trade deficit.
(From: A.J.H. Latham & Heita Kawakatsu (Eds): "Intra-Asian Trade and the World Market", Routledge: London, New York, 2006, p174.)
Japanese exports of textiles amounted to 63.6% of total exports in the period 1917 to 1926, and 56.8% between 1927 and 1936 (source: W. J. Mcpherson, 'The Economic Development of Japan')
After 1930, things changed and Japan began to run a trade deficit with the US. This was offset (at least in part) by reversing or at least reducing the trade deficit with India and South East Asia. Japan was able to expand into new markets during the depression (1931 to 1934) and by 1940 Japan was exporting more heavy manufactured goods than she was importing.1
It would appear that Japan was using this surplus to help pay for the oil (i.e. multilateral settlements). Note also that
Japanese exports grew faster than world exports, faster than other variables and, in the cotton industry, the export output ratio rose from 1.5 per cent in 1890 to nearly 56 per cent in the 1930s.
It should be pointed out that the Japanese government allocated quotas to companies for oil imports (at least from 1934) and thus (as far as I can see) did not import oil itself. The 1934 Petroleum Industry Law favoured local refining operations (and Japanese companies, but American companies such as Standard Vacuum Oil and Tidewater Oil continued to operate), and the government purchased from them. It would thus be wrong to look at oil imports as being 'directly' paid for by the Japanese government. Nonetheless, earnings from exports of textiles and manufactured goods were key to the government's ability to purchase oil from private oil concerns in Japan. Government finances also drew on government bonds issued through the bank of Japan, and the Japanese government ran a deficit throughout the 1930s.
1 Janet Hunter and S. Sugiyama, 'Anglo-Japanese Economic Relations in Historical Perspective, 1600–2000: Trade and Industry, Finance, Technology and the Industrial Challenge'. In Janet Hunter and S. Sugiyama (eds.), 'The History of Anglo-Japanese Relations, 1600-2000: Volume IV: Economic and Business Relations' (2002)
The Japanese Economy during the Interwar Period (Bank of Japan review)
Kerry A. Chase, States, Firms and Regions in the World Economy