Square Enix is releasing Lost Sphear, a spiritual sequel to I Am Setsuna. This game is being made by Tokyo RPG Factory and will be released on January 23, 2018. If you wish to get it sooner you can buy it from the Japanese eShop on October 12, 2017 or import a physical copy.
Square Enix has given this description of the game:
The next evolution in this new golden age of JRPG’s arrives with LOST SPHEAR, bringing a fresh take on classic RPG gameplay! A young man, who suffered a phenomenon that he had never seen, faces an ominous power that threatens the fabric of reality. Awaken the power of Memory to restore what was lost! Muster different Memory and craft the world around you in a journey to save the world.