Not sure if it matters to you or not (it does to me for my trip).

From Japan-Guide:

Construction Notice: Major renovation works will be carried out on the main keep of Himeji Castle from mid 2009 to 2014. The main keep will be covered by scaffolding for most of the duration (starting around autumn 2009), and access to the interior of the main keep will be partially restricted.

link: http://www.japan-guide.com/e/e3501.html