Last week, we learned that GungHo Online was making a sequel to Puzzle & Dragons Z for 3DS, which was released in the states bundled with Puzzle & Dragons: Super Mario Bros Edition. Unfortunately, not much information was revealed at the time, but that changed today.
The sequel will be called Puzzle & Dragons X and, like its predecessor, will offer a mix of tile matching puzzle solving and monster collecting and battling RPG gameplay on 3DS. This time around, the game will expand on the RPG elements while also offering more game in general than the original, which translates to a total of 500 monsters in the game along with allowing the player character to play a more active role through equipment and abilities.

Nothing has been said regarding a worldwide release for Puzzle & Dragons X, but a 2016 release for Japan has been confirmed.
Source: Siliconera