National Institute of Japanese Literature　[English]   http://www.nijl.ac.jp/index_e.html
国文学研究資料館 　[Japanese]   http://www.nijl.ac.jp/
Includes not only important bibliographical databases, such as Nihon Kotenseki sōgō mokuroku, but also several full-text and image databases.  Must register to use.

The Museum of Modern Japanese Literature   http://www.bungakukan.or.jp/
日本近代文学館

International Research Center for Japanese Studies　[English]   http://www.nichibun.ac.jp/welcome_e.htm
日文献　[Japanese]   http://www.nichibun.ac.jp/
Nichibunken has created many databases, especially on art (foreign images of Japan, Japanese art in overseas collections etc.) but also provides Enpon. collections of renga, waka, haikai and Japanese folktales.  Some databases can only be used at Nichibunken.

International Library of Children's Literature   http://www.kodomo.go.jp/english/index.html
A branch of the National Diet Library.  Its digital gallery includes Edo picture books and Kodomo no kuni, Artist and children's books in 1920s Japan. 

Performing Arts Network Japan    http://www.performingarts.jp/

Japanese Society for Theater Research   http://wwwsoc.nii.ac.jp/jstr/
日本演劇学会