Once a noble and kind fairytale prince, he lived to protect the weak and the needy. His heart was shattered to seal the monster Raven away. Now a talented and popular student at Gold Crown Academy, he possesses no emotions, nor memories of his past life, and is largely dependent on Fakir for his well-being. When Drosselmeyer decides to use Duck to become Princess Tutu, she gathers the lost heart shards of Mytho's heart and returns them. Meanwhile, Rue's alter ego emerges from her and becomes Princess Kraehe , trying to possess him for herself. When she soaks Mytho's heart shard of love in the Raven's blood and when the shard is returned by Princess Tutu, Mytho struggles to free himself from the blood and then transforms to a crow later. Rue then reveals her feelings to him saying the words, "I love you!" and he becomes restored to a human. The last shard of his heart, which was Princess Tutu's pendant, is returned to him and he becomes Prince Siegfried again, defeating the Raven and asks Rue's hand in marriage before he returns to the story.
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. It begins with negative heart shards only to get positive towards the finish. As Prince Siegfried, he is very brave and noble but as the Prince of Crows, he is deceitful and coarse towards others, even Fakir and Rue.
Mytho is a young man with silver-white hair and large amber eyes. He mostly wearing Gold Crown Academy's uniform but in other times, he wears a white long-sleeved blouse that consists buttons and a collar. At ballet class Mytho wears a white short-sleeved shirt, black pants, white stockings, and white ballet slippers. While having the Raven's blood flowing inside him, his outfit as the Prince of Crows is a black outfit and with wings on his arms that grey. Later on when his heart became fully restored in episode 25, he wears a gold crown on his head and a long-sleeved royal blue tunic with gold lining designs, a collar designed with long white feathers, and an iris blue chemise worn underneath. Mytho also wears a white hose, a white cape, and white ballet slippers.
Duck/Princess Tutu: Duck is one of his many admirers. Mytho does not notice her at first, but eventually grows to think of her as a friend as he regains his heart. Princess Tutu, on the other hand, becomes someone Mytho both longs for and fears for reasons he doesn't understand.
Rue/Princess Kraehe: Rue has been in love with Mytho since she was a little girl, but though he treated her kindly, he could not return her love without his emotions. The two appear as a couple at first, but only out of Rue telling Mytho to be hers. When he is corrupted by the Raven's blood, he treats Rue and Kraehe with scorn and mocks her constantly. However, when Mytho regains his past identity and Rue shows her willingness to sacrifice herself for his sake, he realizes that Rue is his true love, and makes her his princess.
Fakir: Fakir is Mytho's roommate and protector. The majority of what Mytho does is under Fakir's orders. The Prince of Crows seems to take sadistic pleasure in tormenting Fakir's cowardice.
- His true name, Siegfried, is the name of the prince who fell in love with Odette in Swan Lake
- His common name, Mytho, may refer the term Mythos which is the set of rules that govern the universe in which a story is placed.