There is a kind of sacred creature in the world - feathered beasts. They have human bodies but have a pair of wings. The feathers on their wings can bring warmth to the world.
At first, feathered beasts and humans lived peacefully, helping human beings live and develop. Later, some humans were not satisfied with their income and began to squeeze and kill feathered beasts for their single-minded greed. The Emperor of the Feathered Beasts, the Feathered Emperor, found out about this and was furious and started a fierce battle with humans. Due to the oppression and killing of humans, the Feathered Beast clan was defeated and forced to flee back to the Feathered Realm and closed the door between the Feathered Realm and the Human Realm.
Tens of thousands of years later, a feathered beast accidentally fell into the human world and gave birth to a child - Yi, with a human. When the Yu Emperor found out, he took her back to the feather world and locked her up, but the child was missing.
Sixteen years later, Yi met Capas Will in the slums.
Concept: all kinds of things in the world