Chains of Freedom

Skye has been a slave along with her sister, Aliana for the past three years. Then, one day her sister finds a creature who calls him-self kyubey. And, he says her will make a contract with her and grant her a wish, but she will be destined to fight witches for the rest of her life. She knows what her wish is, to get out of this mess of slavery but is it worth it to have to fight witches and take the chance of dying and leaving her sister but will things get bad enough for her to have to make the wish?