Blizzard announced the release of the next expansion package for the Diablo III Reaper of Souls. The package is called “The Rise of Necromancer Pack” and it will be available from June 27, 2017 on PC, PlayStation 4 and Xbox One in North America and Europe. The price will be 14.99 USD in the USA.
The Japan, PC version’s server will be under maintenance on June 28, 2017 so maybe after it you can buy the Japanese edition. Blizzard already updated the Q&A page where you can read all the details about the package with questions and answers. You can find it in here: https://us.battle.net/d3/en/blog/20324407