A Duel Monster and the main character of the Diabellstar card storyline from Yu-Gi-Oh!.
Diabellstar is a treasure hunter who seeks to collect the "Sinful Spoils", magical artifacts with immense power. She normally has grey hair and yellow-ish grey eyes, though her right eye will turn green once she dons her red half mask (which is also another "Sinful Spoil" in her possession).
Initially introduced as a calm and stoic character, but later cards reveals that she is quite expressive and somewhat hot-headed.