This game was announced for the PS Vita in Japan. It is a version of Ys IV that was actually made by Falcom itself. The other Ys IV games that were released in the past are Mask of the Sun (SFC) that was developed by Tonkin House and Ys IV: Dawn of Ys (Turbo-Duo) that was developed by Hudson Soft. There was also a remake of Mask of the Sun, done by Taito, called Mask of the Sun ~ A New Theory.

What I know about the features of the actual Falcom make of Ys IV are the following:

- The game will use Ys Seven's battle & party system
- Its a re-imagining of Ys IV: Mask of the Sun
- This version of Ys IV will have explanation on how Adol became an adventurer
- The game will make use of Vita's touch screen controls for actions and puzzle solving situations.

Feast yourself on a nice trailer to see what CSoT is like
Celceta Sea of Trees trailer