Created by Professors Daniel Botsman and Rustin Gates (Bradley University), this bibliography contains dozens of Western accounts of travel to Japan, beginning in the 16th century. The sources are grouped chronologically, and are linked to their respective Orbis records.
To search for works on early and medieval Japan in English, use an Orbis keyword search with English set as a limit. (The 'Set Limits' tab is located to the lower right-hand side of the search box.) Try 'Japan history medieval', or 'Japan history' and a relevant date.
Note that LC subject headings break down early Japanese history along key dates such as 645, 794, 1185, 1333, and 1600; keyword searches that include these dates will return those records falling under these subject sub-headings. See Reiko Yoshimura's website for more specifics, as well as useful subject headings for specific events in the pre-Tokugawa period.
The Historiographical Institute at the University of Tokyo offers a wealth of online resources: most of their databases are in Japanese, but the On-line Glossary of Japanese Historical Terms (located under 'Tools') allows you to search for terms in English, French, German and Japanese (romaji, hiragana, and/or kanji). The database returns works (in all these languages) that contain the relevant term, and also serves as a useful tool for translation. To search using a non-Japanese term, enter the term (or terms) and click the 全文検索 button; to search using a romanized term, click the 語彙検索 button.
For help with Japanese dates, refer to Tsuchihashi's chronological tables.
John Dower's Japanese History and Culture from Ancient to Modern Times: Seven Basic Bibliographies contains a chapter devoted to the historiography of ancient and pre-modern Japan, with some translated primary sources.
John Bentley's Historiographical Trends in Early Japan provides a helpful overview of the material and sources available from the early medieval periods.