After accidentally letting the eight Harmony Tones fall into the hands of a sorceress named Siren, the cursed Utau finds herself as an outcast amongst the many people in her home. Until Siren decides to pour salt in the wound by slowly turning everyone to stone starting with the outskirts of town and moving to the castle. One day a cursed cat named Clef entitles Utau's help to un-stone the kingdom and collect the tones, breaking the curse on both of them.
- A cursed girl who accidentally gave the Harmony Tones to Siren. She has the legendary crystal voice which can attract Harmony Tones if they were to escape. Overall, Utau has been seen as strange due to her curse, but after getting to know her, she's caring and helpful but has her limits.
- Cursed to become a cat, Clef is the prince of Symphonia who went missing when Dissonance made themselves known. A bit of a downer at times, he always tries to think on the positive side. As the story progresses, Clef finds himself acting more cat like, slowly forgetting his humanity.
- Harmony Tones
- Harmony Tones (also known as Soflège in old texts) are eight tones that protect Canon in times of need. They have a fondness to Utau due to her voice.
- Disharmony Tones
- Being infused with Siren's magic, the Harmony Tones find themselves creating chaos around them. They have a lack of morals.
- The Royal Family
- Consisting of King Resonance, Queen Serenade and Prince Canon (Clef)
- Symphonia - Utau's hometwon and the main setting of the show/manga
- Cressendo Box - A box that held/holds the Harmony Tones.
- Star Locket - A locket that Clef gave to Utau in the first episode
Crystal Solfège has twenty four episodes in the series
Crystal Solfége has six manga volumes and two side series volumes