Snow of Ashes

Fifteen years ago, the war launched by the pagans caused the light of Starlight City to disappear, the city was filled with ashes, poisonous snow fell, and people were forced to wear ash clothes to go out. Nothing changed until I met the legendary culprit known as the white-haired witch... The strange sounds echoed in my mind, the dark shadows I dreamed about repeatedly, and the snow became heavier and heavier. Who am I?