CiNii is a bibliographic database service for material in Japanese academic libraries, especially focusing on Japanese works and English works published in Japan. The database was founded in April 2005 and is maintained by the National Institute of Informatics. The service searches from within the databases maintained by the NII itself [NII Electronic Library Service (NII-ELS) and Citation Database for Japanese Publications (CJP)], as well as the databases provided by the National Diet Library of Japan, institutional repositories, and other organizations.
The database contains more than 15 million articles from more than 3600 publications. A typical month (in 2012) saw more than 30 million accesses from 2.2 million unique visitors, and is the largest and most comprehensive database of its kind in Japan. Although the database is multidisciplinary, the largest portion of the queries it receives is in the humanities and social sciences field, perhaps because CiNii is the only database that covers Japanese scholarly works in this field (as opposed to the natural, formal, and medical sciences which benefit from other databases).