An Awakening can either level up the art being used, or unlock a new one related to it. (perfectly-nintendo.com)
Completing the first few songs available unlocks new ones, and each song has prizes for completing them with a certain score. (destinyislands.com)
There are multiple playable characters to explore the open - world environment with, including some familiar faces from NieR, and will be able to unlock new ones with each playthrough. (heavy.com)