Duck is the protagonist of the series. She is a friendly, kind-hearted duck who was given a magic pendant, which turns her into a teenage girl. This pendant also allows Duck to turn into her alter-ego, the wise and graceful Princess Tutu.
Duck was an ordinary yellow duckling until she saw the princedancing on the lake and looking lonely. Hearing her desire to bring him happiness, she was given a pendant by Drosselmeyer which gave her the ability to transform into Princess Tutu. If Duck removes the pendant or quacks while talking, she transforms back into a duck and must touch water while wearing the pendant to return to her human form.
Later on, to save Mytho, her pendant gives her the power to transform into Princess Tutu. Because she is now a part of Drosselmeyer's story, Duck/Tutu will turn into a speck of light and vanish if she confesses her love to Mytho. Nonetheless, Duck continues to transform to help return his missing heart shards back to him.
Fakir is Mytho's roommate and a talented ballet dancer at Gold Crown Academy Drosselmeyer's story The Prince and the Raven included a knight who was to protect the prince and ended up dying, cut in half, by the claws of the raven. Fakir is thought to be the reincarnation of said knight from the story due to the scar-like birthmark that cuts across his chest, like the wound that ended the knight in the fairy tale. When he found Mytho as a young boy, Fakir decided to take on the role of the knight and be the heartless prince's protector..Duck, she also has a princess alter ego, the seductive and unkind Princess Kraehe.
When she was a baby, Rue was stolen from her parents by a group of crows who served her adoptive father, The Raven, who named her Kraehe. She grew up believing herself to truly be the Raven's daughter, who by some strange twist of fate, ended up being trapped in an "ugly human body".Drosselmeyer, who shattered his heart in order to defeat the Raven.
Mytho is utterly emotionless at the beginning of the series so he seems unable to think for himself and listens to almost anything told to him. With the help of Princess Tutu returning his heart, he begins to develop emotions and slowly returns to the way he was long ago.
Years before the opening of the series, Drosselmeyer was a writer that was working on his masterpiece, The Prince and the Raven. However, before he could complete his story, he died, leaving his story unfinished and the two title characters trapped in an endless battle. Eventually, the characters were able to leave the story—and it turned out that Drosselmeyer, while dead, could somehow control the story even from the grave.