Sara

Sara is Kagetsus sister and Tiaras childhood friend. A sweet gentle girl with a weak constitution she has untapped ability as a Neutralizer. She mysteriously disappeared before the Throne of Yord incedent began. It is implied at the conclusion of the Throne of Yord Saga and is indeed the thing that saves Tiaras life that Sara is and always has been a part of the Throne of Yord and that she was destined to joined to it from birth. Source: Wikipedia