Some 40 reference books below are searchable at once, or individually.
Nippon Style: Visual database for Japanese Products
Tangorin English-Japanese and Japanese-English dictionary.
Kotobank Search 99 dictionaries and encyclopedias at once.
辞典横断検索 Metapedia Search 551 reference books at once.
語源由来辞典 Japanese Etymological dictionary
古事類苑 Koji Ruien (1933). Digitized by Internet Archive.
古事類苑全文データベース Koji Ruien full-text database (Nichibunken) on-going project
Digital Dictionary of Buddhism 電子佛教辭典 ID
Edited by Charles Muller, the dictionary provides English definitions for Buddhist terms in a range of languages, including Chinese, Japanese, Korean, Pali, Sanskrit, and Tibetan, as well as pronunciations. It includes A Dictionary of Chinese Buddhist Terms : with Sanskrit and English equivalents and a Sanskrit-Pali index, compiled by William Edward Soothill and Lewis Hodous.
JAANUS: Online dictionary of Japanese Architecture and Art Historical Teminology Compiled by Dr. Mary Neighbour Parent
府県統計 Prefectural statistics from the Meiji period (1868-1911)
Ministry of Finance Statistics 財務省統計資料
Statistics for the ast five years pertaining to the government budget, government bonds, trade, balance of payments, etc.
Ministry of Health, Labour and Welfare Statistics 厚生労働統計一覧
Ministry-issued statistical data.
JETRO Trade and International Payments Statistics 日本の貿易・投資・国際収支統計
Trade, investment, and income and expenditure statistics.
Economic Statistics and Public Opinion Polls / Surveys 内閣府 統計情報・調査結果
Opinion polls and surveys are accessible at the bottom of the page under the heading その他.
NHK Broadcasting Culture Research Institute, NHK, 放送文化研究所
Survey results provided under 研究・調査. Poll results available under 一般世論調査. Polls and surveys were conducted by the institute over the past few years. Brief English-language summaries of some reports are available under "Surveys and Research Results" at http://www.nhk.or.jp/bunken/english/.
Data Archive, Social Science Japan
The Social Science Japan Data Archive (SSJDA) collects, maintains, and provides access to quantitative data from social surveys for the academic community. Data is provided in Japanese only, but there is an English version of the website with information on how to deposit and access data. The archive is maintained by a unit within the Information Center for Social Research on Japan, Institute of Social Science at the University of Tokyo.