Ahiru Arima

Ahiru which translates to duck in Japanese is in all reality a duck herself however in the beginning of the series she was turned into a human girl by Drosselmeyer. He also bestowed upon her a pendant which causes Ahiru to transform into her otherself Princess Tutu. This was all caused by her desire to see Mytho the Prince of the story smile. It turns out her role as Princess Tutu is to gather Mythos missing heart so he can gain back the many feelings of sadness and happiness.