CiNii Dissertations Open : could be one stop shopping for Japanese Dissertations
Great news for oversea Japanese studies researchers and librarians.
NII opened new dissertation database in June 9, 2015. It cover 600,000 dissertations (Ds) with bibliographic info only from NDL, 131,000 Ds with links to full text and TOC, and 130,000 Ds with links to full text and some with abstracts.
Please try it (English interface)
Information about (English)
Review of CiNii Dissertations by a Japanese university librarian (Japanese)