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Japanese Studies (in Japanese)
This is a general purpose set of links that I use almost daily to do research using Japanese language resources
Fabulous online chronology that lists major events in publishing history, titles, and what was happening in the world at the same time.
In general, copyright protections extend 50 years beyond the death of the author in Japan and 70 years beyond the death of the author in the United States. Copyright protections may be extended or sold as well.
You would think that information about books would be easy, but it isn't. There used to be an annual publications called 著作権台帳 published in print. It has ceased publication. Now you need to check the author's dates in NDL OPAC, the name listed on the colophon, and check with publishers.
This is the website to consult in either English or Japanese for the laws, case studies, and general Q&A about copyright concerns. See also the links to organizations that protect the rights for different kinds of materials (music, dramas, literary)