According to the Japanese developer, the game is for a system that has yet to be released.
In a Famitsu interview, Level 5 CEO Akihiro Hino revealed that they are working on a new title that deals with time traveling for a system that hasn't been released. Naturally, that led to speculation that the game might be for Nintendo's new handheld, the 3DS.
The storyline for this unknown title will be penned by Jiro Ishii, who worked with Sega on the Japanese-only Wii game, 428. Hino said that this new game has the potential to be a popular series for Level 5.
Level 5 is known best for the Professor Layton series, their work on the most recent Dragon Quest titles, and the Dark Cloud series. In North America, their next release will be Dragon Quest IX, which is slated to come out this summer for the DS and will be published by Nintendo.