History Summary: Duck is, originally, a cute little yellow duck, plain and simple. One day a prince started dancing on her pond. She thought the prince was beautiful but noticed his sad eyes and wanted to see him smile. The next thing she knows she's a 'normal' girl studying ballet in the same school as the prince, and she turns into Princess Tutu on occasion to collect the shards of his shattered heart and return them to him. The prince is actually the hero from a fairytale called "the Prince and the Raven". The tale was left unfinished when its author died, and the characters escaped from the story. Still, from beyond the grave, the author is still manipulating the course of events. And he's sadistically dedicated to insuring the most tragic end to his posthumous magnum opus.
The author, Drosselmeyer, was the cause of Duck's sudden transformation. He gave her the pendant which enables her to maintain her human form and her into Princess Tutu. As Duck, she looks for the shards of the Prince's shattered heart. As Princess Tutu, she coaxes them out of their hiding places in other people's hearts and returns them to the prince, but it's no easy task. There are two people who don't want the Prince's heart to be returned to him: Fakir, who has taken care of the Prince since he was very young, and who gave the Prince his name, Mytho, and Rue, the proud, cold star of the advanced class who is Mytho's self-proclaimed girlfriend.
Fakir doesn't want Mytho's heart returned because that will enable him to feel pain again, and Fakir is overzealous in his protection of Mytho, fancying himself Mytho's Knight, like the knight in the story of the Prince and the Raven, who gave his life for the Prince. Rue, on the other hand, takes advantage of Mytho's heartlessness to dictate to him how he should feel, to tell him that he loves her, and she fears losing him if he begins to regain his own feelings.
As Duck returns more and more heart shards to Mytho, her path becomes more and more difficult. Many of the heart-shards she returns grant Mytho the ability to feel negative emotions, namely pain, loneliness, and fear. She begins to question whether what she's doing is truly for the good, as the emotions she's returning cause him to suffer. What's more, she initially did not know anything about the story she was being written into. She soon discovers that Princess Tutu existed in the original "Prince and Raven" story, where was not destined to live happily ever after with the Prince. The Prince was fated to another, and Princess Tutu was cursed to turn into a speck of like if she ever confessed her love, which she did, after returning the Prince's heart. Duck realizes that she can never tell Mytho how she feels about him if she wants to live. She also encounters active resistance on Fakir's part.
Then, when it appears that Mytho is becoming attached to Princess Tutu, a new problem arises - Rue's jealousy of Tutu awakens her hidden persona, Princess Kraehe! Kraehe steals shards from Tutu's very hands, and is beaten back by Fakir. Fakir makes his position clear to Princess Tutu - his goal is to protect the Prince, and he considers Tutu as much of a threat as Kraehe. But over the course of the last little while, Duck has come to understand that Fakir is not as bad as he seemed, and didn't want to fight him, and suggested that they cooperate in helping Mytho. Fakir refuses, and even goes so far as to try and shatter Mytho's heart again, but Mytho expresses his desire to find the rest of his heart, and Fakir realizes that ultimately, he can't go against his prince's wishes. He is still, however, reluctant to cooperate with Princess Tutu.
The next time Princess Tutu finds a heart shard, Kraehe opposes her, and is again chased off by Fakir. But Kraehe hatches a plot to neutralize Princess Tutu, and it comes into effect just as she is returning the heart shard of love to Mytho. With the shard only halfway in, and Tutu tied up, Kraehe appears and rips it out of her love's breast, and disappears, prince and all, from the scene.
Finally, with Mytho kidnapped, Duck and Fakir agree to work together to find the Prince and defeat Kraehe. They make their way to Kraehe's underground lair, where the 'final confrontation' is to take place. Mytho is there, but in a near-catatonic state, and Kraehe is holding the love shard, and the unconscious Prince, as spoils in the upcoming contest. Her terms: each girl must speak their love to the heart shard, and whoever it is most drawn to is the victor. In this way, she hopes to trick Princess Tutu into confessing her love to the Prince, and disappearing. But Tutu manages to avoid her fate by expressing her love through dance, instead, and though the heart shart chooses Kraehe, Mytho himself chooses Tutu. Defeated and heartbroken, Kraehe retreats, and Tutu returns the feeling of love to the Prince.
Unfortunately, her triumph is short-lived. Kraehe had prepared for such an occurrence. Before the confrontation, she had infused the heart shard of love with Raven's blood, which would slowly corrupt the Prince's heart and place him under Kraehe's thrall and that of her father, the Monster Raven, and Mytho's old nemesis from the story. Mytho begins a mission in the service of the Raven: steal pure hearts to feed to the monster. He is always foiled by Tutu and Fakir. The Raven's taint pains him, but as time goes on, it consumes him more and more, twisting his personality and his original identity as The Prince who Loves Everyone and is Loved by Everyone.
Duck may continue to return heart shards to him, but she doesn't know how to purge the taint from him, and Fakir has no more of a clue. Soon all of the heart shards hiding in people's hearts have been collected and returned to Mytho, and the only shards left are the ones sealing the Monster Raven. As Mytho's condition degenerates, Kraehe begins to question the wisdom of her decision to corrupt him - he's becoming increasingly unstable, and even violent toward her. This is not what she expected of a Raven Prince who would love only her. He even begins to toy with the idea of sacrificing his own heart to the Monter Raven. Meanwhile, Duck and Fakir feel helpless - Duck has almost outlived her usefulness as Princess Tutu, and Fakir is realizing that there is only so much he can do with his sword.
During this time, a woman named Raetsel, who was something of a surrogate big sister to Fakir, visits the town, and Duck asks her about Fakir. Raetsel tells her something very interesting: as a child, Fakir used to write stories, and sometimes these stories would come true. Duck immediately runs to Fakir to tell him what she's heard and suggest that he write a story to solve their problems, but Fakir refuses. He had buried all memory of his unusual power because of a traumatic incident in his past: when he was a child, a great many ravens came to his town and terrorised the population, so young Fakir decided to write a story in which he became a hero and defeated the Ravens. The story came partially true - he had written that the ravens would attack him, but when they came, his parents protected him, shielding him with their bodies. They died for him, and from that day on, he never wrote another story.
Still, it seems that writing a story may be their only chance of saving Mytho, so Fakir, with great reluctance, decides to start writing again. A boy named Autor appears, claiming that Fakir is the direct descendant of Drosselmeyer, and offering to train Fakir in the art of story-spinning. Fakir accepts and is put through ridiculously gruelling training, such as standing in place for three days with no food, water, or sleep, and having ice-cold showers to 'purify' himself before starting to write. Duck busies herself with locating the shards sealing the Monster Raven, so she can return them to Mytho when the time comes. Despite this, she still feels helpless - what could she do but collect the heart shards which obviously weren't helping Mytho's situation? How could she help him when it came time to fight the Monster Raven? What could she do but watch as Fakir struggled with sword and pen to give Mytho a happy ending? In the end, how much use could she be? Fakir himself is discovering that he can't write stories about himself or Mytho - when he tries, the words do not come.
Autor is not the only one who has taken notice that the town is caught in a story - a secret society of really old dudes called the Bookmen, who were the ones responsible for severing Drosselmeyer's hands and for killing him, has found out about Fakir, and they think he is the one weaving the current story. Just as Fakir's hands are about to be chopped off, Duck transforms into Princess Tutu and manages to pacify the bookmen. She reassures them that Fakir does not intend to use his powers for evil and that they are trying to end the story happily. As soon as this is accomplished, Drosselmeyer, angered by the bookmen's interference in the story, kidnaps Duck and takes her to the clockwork world inside the story where he tries to coerce Duck into following his plans for his tragic story.
Fakir's third attempt to write a story- with Duck as his main character, is finally successful. His story frees her from Drosselmeyer's clutches, and begins turning time backward. Now we cut to Rue and Mytho. While Fakir and Duck were trying to save Mytho, Rue was still dealing with an increasingly raven-corrupted prince. By this point, Mytho has actually turned into a man-sized, anthropomorphic raven, and Rue sees nothing else to do but tend to him. As time turns back, Rue begins to remember events in her past that she had long forgotten. Though she had always been told that she was the Monster Raven's biological daughter in human form, she discovers that she was actually human, stolen from her parents as a baby and nursed on Raven's blood. The revelation cuts through all the lies her adoptive father had told her throughout the years, but only plunges her further into sorrow. She is not special. She is not worthy to love the Prince. All she's ever done is hurt him.
Returned to the real world, Princess Tutu soon discovers one final secret: the pendant she wears that enables her to turn into Princess Tutu is the Prince's final heart shard, representing the prince's will to recover his heart. Encouraged by this revelation, she sets about collecting the shards which seal the Raven and give them to him. When all shards but the pendant have been returned to him, and the Raven appears over the town, Mytho flies away, intending to give his heart to the Raven. Princess Tutu tries to stop him, but to no avail. Despairing, Rue confesses her love to Mytho and begs the Raven to eat her heart instead. This confession of True Love by Rue is enough to break the raven blood's hold on Mytho's heart, but not before the Raven swallows Rue whole.
Now that nearly all of Mytho's heart has returned and he's been freed of the dark taint, Mytho's next concern is to free Rue from the Raven. He tells Princess Tutu that Rue's love has touched him and that he wishes to make Rue his princess. He asks for Tutu to give him her pendant, the final heart shard, but when Tutu goes to comply, she finds she can't unfasten the pendant. The Raven becomes angry. Eating the Prince's incomplete heart will not grant him immortality, so he captures the Prince and delivers an ultimatum. If Princess Tutu does not restore Mytho's heart by dawn, he will kill the Prince. Tutu retreats in shame.
Fakir, meanwhile, is still setting to work writing, when he is interrupted by Drosselmeyer, who begins forcing him to write a story in which Duck throws herself into the Lake of Despair. She wonders why she can't take off her pendant, and Drosselmeyer within the story tells her it's because she selfishly wants to remain with the Prince, that she doesn't want to be just a duck again. Fakir stabs his hand rather than continue writing such a tragedy, and rushes out the door to find Duck. They perform a pas-de-deux, on the floor of the lake of despair - he reassures her that it's normal to not want the story to end, tells her it's okay if she's a duck, inspires her. They decide to protect Mytho from the Raven together not just for Mytho's sake, but for the stricken town which is under the Raven's thrall. Fakir promises Duck that even though she'll go back to being a plain old duck, he'll always stay by her side.
They return to Autor's town house, and Duck becomes Princess Tutu one final time, while Fakir writes her story. She gives the Prince his final heart shard back and turns into a duck. The Prince is then restored to his full power, but Drosselmeyer and the Raven have a few more tricks up their sleeves. The Raven had turned the entire population of the town into crows, and set them against the Prince. Facing so many foes, foes which he couldn't defeat or else risk killing an innocent person, he could do nothing. Duck, no longer anything other than a duck, could do nothing. Fakir though he tried desperately to change the story for the better, could do nothing but write events as they happened. Rue, inside the Raven, sinking to the depths of despair, could do nothing but dance sorrowfully.
But Duck would not give up. Although she was not Princess Tutu any more, she could still dance, and through dancing convey her feelings. So she danced a dance full of hope, and with the help of Fakir inspired Mytho to gather his strength and rescue Rue, and with hope they defeated the monster Raven, freeing the village from his spell. After the Raven was dead, they found the mechanism by which Drosselmeyer was able to write even after he died, and Fakir destroyed it. Mytho took Rue for his bride, and they flew away into the horizon in a swan-drawn carriage, happily ever after. As for Duck and Fakir? Well, Fakir is writing a new story, and the little yellow duckling never leaves his side.