I am considering exporting pharmaceuticals marketed in my country to Japan for the first time. Can foreign manufacturers obtain approval directly? Also, is the data on stability tests and clinical tests performed outside of Japan accepted as test data for the applications for import approval? 

Foreign manufacturers may directly obtain an approval from the Minister of Health, Labor and Welfare. In such cases, manufacturing/selling operations of the imported pharmaceutical can only be conducted by the manufacturing/selling business entity which the foreign manuracturer so chose when applying. Furthermore, test data conducted overseas are accepted if they satisfy certain conditions.

1. To conduct a manufacturing-selling operation of pharmaceuticals manufactured in foreign countries, a foreign manufacturer can directly obtain an approval from the Minister of Health, Labor and Welfare (Foreign Special Approvals). When applying for the Foreign Special Approval, the manufacturer must choose an entity with a permit for manufacturing/selling business in Japan, and manufacturing/selling of the imported pharmaceuticals is only allowed for this chosen entity (Selected Manufacturer-Seller). In addition, to conduct wrapping, labeling, or storage operations after importation, an entity requires a manufacturing permit as well.
Upon exportation of pharmaceuticals, quasi-drugs, and medical devices to Japan, the manufacturing factory must have a Foreign Manufacturer Approval.
2. As for pharmaceuticals, data on stability tests conducted overseas may be accepted as long as the tests follow Japanese regulations and guidelines (Notification by the Director of the Pharmaceutical Affairs Bureau on February 15, 1991). For clinical tests, results are accepted, in principle as the documents for the judgement if (1) the test is conducted under the standard based on the Ministerial Ordinance on the Standard of Clinical Examination for Pharmaceuticals and also on Article 43 of the Enforcement Regulation of Pharmaceutical Affairs Law, and if (2) the data is qualified as to meet the standards above by the certification based on Article 14:5 of Pharmaceutical Affairs Law or the on-site inspection. The clinical test data conducted in Japan is also required in principle for the judgement whether the data overseas can be used for the assessment of efficacy and safety of the drug in Japanese.
3. Quasi-drugs and cosmetics are also treated in a similar fashion. (In addition the same can be said for Foreign Special Approval applications for cosmetics and medical devices.)