På Princess Tutu ges Ahriu ett hängsmycke som upptäcker delar av prinsens hjärta och låter henne omvandlas till Prinsessan Tutu så att hon kan returnera dem till honom.
I den näst sista episoden,
Ahiru tries to avoid giving Mytho the last piece of his heart, because it's actually the gem she's been using to turn into Princess Tutu - and without it, she'd revert to her true original form, a duck.
But I don't recall it being stated just what that piece of heart was. I thought it might be Love, but that was in Akt 11 La Sylphide. Wikipedia and the rest of the Princess Tutu wikia doesn't say, so does anyone know which emotion turned Ahiru into Princess Tutu?
Bonus points if you also know what the shards from the five gates to the town were.