From Esthétique:

Arianrhod is a young girl from an island called Erin. She is different from all the other kids her age. All the others in the tribe have blond hair while Arian is the only one with black hair and because of this she was bullied many times. One day a traveler in silver clothing came to Erin and “named” Arian. To be named is very important because it reveals one's true self. After that the Master Drisu takes Arian in as his disciple because she was “named” by the stranger. Balor is the evil leader of Death Valley and one night he murdered all the people in Arian's tribe, and she swears to get vengeance on Balor.