Revenant Kingdom takes a different tale from the previous titles with the main character King Evan Pettiwhisker Tildrum, who was usurped from his kingdom. The story revolves around how he would regain the throne back with the help of Roland, a visitor from another world.
The reveal in PSX 2016 came in a form of a trailer video (that you can see below)
Ni No Kuni II is developed by LEVEL-5 and has a 2017 release date. For more info, you can check out the Ni No Kuni II: Revenant Kingdom site and fanpage.