Princess Tutu (プリンセスチュチュ, Princess Tutu?) is a magical girl anime created by Ikuko Itoh in 2002 for animation studio Hal Film Maker. It was adapted as a 2-volume manga illustrated by Mizuo Shinonome. Both series are licensed in North America by ADV Films.

Princess Tutu includes elements of fairy tales and famous ballets, particularly Tchaikovsky's Swan Lake. The series follows Duck, a duck who has transformed into a young girl who attends school and takes ballet, and her efforts to restore the heart of her mysterious schoolmate Mytho by transforming into Princess Tutu. The series explores the consequences of her actions and how they affect her and those around her, particularly Duck's classmate Rue, who is in love with Mytho, and Fakir, Mytho's childhood friend. It becomes apparent that Duck, Rue, Mytho, and Fakir are meant to play out the roles of characters in a story written by a writer named Drosselmeyer, but the characters begin to resist the constraints of their assigned fates and they fight to keep the story from becoming a tragedy.

Source: Wikipedia