S1·E11 Act 11 - Chapter of the Egg: La Sylphide

Mytho, inspired by an overheard conversation between Duck and her two friends, decides to give a present to Princess Tutu to express his feelings and to find out how she feels. He goes out to town with Rue, where they find Edel selling gems. Edel gives Mytho a gem called Love, but warns him that although beautiful, it can be dangerous and delicate. Rue, aware of the gem's intended recipient, is jealous and scuffs it, then tells Mytho she will shine it and make it even more beautiful. Instead, she curses the gem with hatred and spells a raven's feather inside before giving it back to Mytho. Mytho gives it to Princess Tutu, who discovers the heart shard of love is inside. She is about to return it when Kraehe's hatred manifests and binds her. Kraehe appears and rips the half-returned heart shard out of Mytho's chest.