Saya Takatori

A young girl descended from a long line of white-haired women who have maintained the success of the Takatori household by appeasing the childlike spirit Omamori. She is shy and easily intimidated, apologizing profusely even when the other is at fault.

[Spoiler] At first she is reluctant to let Ushio destroy the barrier imprisoning Omamori, as the backlash of energy would destroy her, but she relents when Tora decides to deflect the backlash. In the aftermath, she tells Ushio of her decision to become stronger like him, and slowly becomes more outgoing and healthier. Oddly, her hair starts turning brown as well, perhaps symbolizing the end of her "job". Like those before her, she has the ability to open the Gates of Hell once in her lifetime. [/Spoiler]

(Source: Wikipedia)