For information on Japan’s national information disclosure law in English, see http://www.freedominfo.org/regions/east-asia/japan/.
This section of the “freedominfo.org” website provides a useful collection of links and articles.
The best source for ongoing developments is www.clearing-house.org (Japanese only).
As I write this, Yukiko Miki’s suit against the Ministry of Foreign Affairs to gain disclosure of its 2012 report concerning Japan’s decision to support the US invasion of Iraq continues.
We prepared a brief press release in English when the suit was filed in July 2015.