Pikmin 3 is also mentioned as one of the titles being worked on.
Shigeru Miyamoto is working on an unnannounced, original title, the designer confirmed in an interview with Zoomin Games.
In the interview, Miyamoto talks about the legacy he has at Nintendo, explaining that many of the developers behind Super Mario 3D Land were once kids that grew up playing Mario games.
Near the end of the interview, it is confirmed that Miyamoto is working on several titles, including Pikmin 3 for the Wii U, Luigi's Mansion 2 for the 3DS and an undisclosed original title. The report doesn't mention which system is the game for.
The full interview follows: