The USDA has Agricultural Trade Offices (ATO's) in both Tokyo and Osaka to provide assistance in marketing foods in Japan,  atotokyo@fas.usda.gov

The ATO has developed the following market reports and guides:

Regulations on sending foods to Japan

The Japanese import regulations require testing of foods entering Japan.  You can become certified for ongoing imports to Japan with the JAS mark (Japan Agricultural Standards) that can be certified by the Oregeon Department of Agriculture.  

The Oregon Department of Agriculture's Export Service Center (ESC) assists companies with pre-export analysis and certification of food products. The ESC is a certified customs laboratory for U.S. foods shipped to Japan, Korea and Taiwan. In addition, seventeen other countries accept ESC analytical results in lieu of testing at the destination port.