A Game That Would Be a Disaster If It Had Hidden/Action Quests

This game has no quests. This is just a hypothetical post... If quests were to be added, conditions like unlocking specific free songs or collecting a certain amount of fragments would be fine, but... If they set conditions based on Potential, it would be a total disaster now. Potential serves as an indicator of a player's skill... If you don't understand this game, they say you can't raise your Potential well even if you play Arkea all day. Also, to raise your Potential, you need to unlock many difficult songs. I've reached level 11 without spending any money. It took about a month.