The Academic Ranking of World University (ARWU) provided by Shanghai Jiao Tong University has released the world top 500 universities of 2016. In the ranking list, Okayama University is ranked at the 10-12th among Japanese Universities. This is a continuous climb in the last two years.
You can find more information in the following web page:

http://www.shanghairanking.com/World-University-Rankings-2016/Japan.html