Donuts is working on a new smartphone game called Lost Kingdom in Japan. The game will be available on iOS and Android in the near future. The official website at the moment has a countdown (which going to reach the 0 in 9 days and 4 hours) BUT you can also watch a short, 35 seconds long promotion video (this video is available above).
Maybe when the countdown reached the 0 we will get more information about this new project. Until that, please stay tuned.