Borderline case here (mostly because of tone), but in some ways Puella Magi Madoka Magica would be great. PMMM isn't a world where you can win just by being hopeful, or having friends, or being dedicated, or what-have-you - things don't work out unless they would really work. And not asking the right questions - or allowing yourself to be led to false conclusions - has very, very nasty consequences.

Of course, I'm not entirely sure I would show that to anyone under the age of 12, and I'd want to be careful about how I dealt with Kyubey's morality afterwards...