Database of materials on Japanese political figures after Meiji (NDL)  http://refsys.ndl.go.jp/hito.nsf/Internet?OpenFrameset
近現代日本政治関係人物文献目録

Japan Center for Asian Historical Records  http://www.jacar.go.jp/index_e.htm
アジア歴史資料センター
In English and Japanese. JACAR was established to provide through the Internet indexes to and digital images of historical records about modern Japan-Asia relations held (and available to the public) by Japanese national institutions. At present, these include records held by the National Archives of Japan, The Diplomatic Record Office of the Ministry of Foreign Affairs, and The National Institute for Defense Studies of the National Defense Agency. Materials included cover from early Meiji times through World War II.

Kindai Digital Library  http://kindai.ndl.go.jp/index.html
Created by the National Diet Library of Japan, it presently includes the full-text of 90,000 titles from the Meiji era, 7,200 from Taishō, and 222 Meiji era photographs. Can be searched by author, title or subject.

Kyoto University Jinbun Kagaku Kenkyūjo   http://www.zinbun.kyoto-u.ac.jp/archive/index.html
Various databases on research on Korea and Koreans residing in Japan, on ethnology and on Southeast Asia. 

MIT Visualizing Cultures  http://ocw.mit.edu/ans7870/21f/21f.027j/menu/index.html
Created by John Dower at MIT, visualizing Culture uses Japan since the mid-19th century as a case study for gaining new perspectives on "cultures" in the broadest since - the "cultures," for example, of Westernization, modernization, changing modes of technology and mass communication, imperialism, nationalism, militarism, racism, commercialization and consumerism, etc.  It begins with the black ships of Commodore Perry and ends with pictures by A-bomb survivors.

Ohara Shakai Mondai Kenkyūjo - Photographs  http://oohara.mt.tama.hosei.ac.jp/kensaku/syashin.html
社会・労働関係　写真データベース
Pre and postwar photographs related to social and labor movements. 

Ohara Shakai Mondai Kenkyūjo - Posters  http://oohara.mt.tama.hosei.ac.jp/kensaku/poster.html
戦前ポスターデータベース

Portraits of Modern Japanese Historical Figures  http://www.ndl.go.jp/portrait/e/index.html
Provided by the National Diet Library in English and Japanese.  Includes a photograph and a brief biographical sketch of 350 statesmen, government officials, military officers, businessmen, scholars and artists.  Can be browsed or searched by category.  Entries cross-linked and author's works are linked to the Kindai Digital Library. 

Teikoku gikai gijiroku  http://teikokugikai-i.ndl.go.jp/
Searchable database of the records of the Imperial Diet from 1938 to 1947 (74th to 97th).

University of Wisconsin Digital Collections - East Asia   http://digicoll.library.wisc.edu/EastAsian/
Included are images that document early 20th century China including the Sino-Japanese Conflict (1937-1945).