Sega of Japan is apparently bringing the party, registering a trademark and logo for Let's Party, presumably the latest in a line of games from developer Prope, responsible for Wii games Let's Tap and Let's Catch.
Sega's trademark with the U.S. Patent and Trademark Office don't tell us much, other than Let's Party is being protected against "video game software; computer game programs" and "providing on-line games; providing information on on-line games." But that pretty much tells us this is a video game and it may have some online component.
Since Let's Catch was a WiiWare title, that "on-line games" mention may simply refer to its distribution method.
Let's Party [USPTO]