The National Diet Library of Japan provides an extremely useful archive of Diet committee and floor discussions. The archive extends back to the founding of the modern state, but only graphic scans of the transcripts are available for sessions prior to May 1947.  All sessions under the current Constitution are available as full-text searchable data, and this is the portion of the archive covered by the translator introduced here.
The site offers a simplified and an advanced search panel. Both offer a rich variety of search options: the advanced search panel (accessible from the middle button in the top-level view above and shown in the illustration to the right) is probably where you want to go. Searches lead to individual session records by way of an intermediate list of search hits, not shown here. The translator wakes up only when an individual session is opened for viewing.
As you can see from the illustration to the right, the session records themselves are a showcase for HTML frames. Details of the record are spread across four separate display areas, creating something of a challenge for the scraping of metadata. The translator operates in “multiple” mode against a session record, presenting a selection list of statements by committee members in the folder-icon popup, as shown to the right. The translator will create a separate MLZ item for each statement selected. The metadata recorded on all items from a specific session will be identical, and researchers may prefer to merge the items together after they are created—because MLZ (like Zotero) preserves all attachments on merged items, the result will be a correct combined item with all portions of the record that have been downloaded.
An individual speaker statement is attached to each downloaded item. Search term markers are removed, and the content is reformatted slightly for readability, but the content is otherwise passed through verbatim. An acknowledgement to the National Diet Library as the source is added to the attachment page header and footer, but in contrast to other translators, no embedded URL is included: the site uses session cookies, making external linking to the records impossible.
This very nearly rounds out support for basic Japanese legal materials. A translator is planned for the Lex/DB case reporting service, but whether that goes forward will depend on the view of the service providers, with whom our faculty has a subscription. After that, we’re likely to start looking at the websites of some of the international organisations.