First of all, forgive me if I misunderstand the direction of the discussion on this subject. I like your Ninja Nights idea because it creates a complex situation with four different interest groups (the monks, the barbarians, the ninjas, and the women), any one group of which may be aware of some but not all of the other players. You might consider consider picking a character from each group and telling a portion of the story from each perspective. There are lots of ways you could go with that.

The current discussion seems to rotate around 'How shall we torture the women?' If that's all it's going to amount to, then what you're left with is just another one dimensional blood orgy. I think this idea could be more than that. The sex should be subordinate to the plot, not the reverse. What are the interests and goals of the various players? It would also be more interesting if the women were more than just pawns and if their suffering was motivated by something more than lust.