Built using the National Diet Library’s publicly available parliamentary minutes API, it brings together proceedings and statements from the House of Representatives and House of Councillors, covering sessions from the first Diet in 1947 through the present. The service lets anyone explore what has been discussed in the Diet, with a searchable archive of more than 11 million statements and records and data updated daily.

Users can search the full text by keyword and narrow results by period, chamber, or committee. The site also offers topic-based browsing across subjects such as taxation, defense, pensions, constitutional revision, and energy policy. Additional features include a ranking of current members of parliament by number of statements, a directory of legislators, and tools for finding representatives by location. By making parliamentary activity easier to investigate, kokkai-data supports research, reporting, and public participation in politics.