NeoGAF. Mission Mode, if similar to the original iteration introduced in Ninja Gaiden Black, drops Ryu into an arena setting and lets him go on a flippin' awesome ninja killin' spree. There is currently no price attached to the new Mission Mode DLC.
The possibility of a Mission Mode should come as good news to NG II players who don't find dressing up Ryu like a Ken doll a worthwhile activity. But, let's be honest, if it's anything like the original Mission Mode, shouldn't it have been shipped with the game or, and we're hoping this is the case, at least be free?