Ninja Crew is finally unlocked when community helped spread enough on Dance Central 2 Challenge app on Facebook and challenges with fellow dancers with the app.
To enjoy the new crew, you will need internet connection. Sign in to your Xbox account and load your Dance Central 2. During your next dance session, the Ninja Crew will be added to your list of playable characters!
Guess it is a Labour Day surprise from Harmonix. Sweet~
|Image from dancecentral.com [Source]|