Familiar tend to reflect the mage summon them, but when you've been bullied for all your life no matter how hard you work, how hard you tried, the world just won't reward you. Then they may chose damnation instead. (Not the best summary, but well...)

It was 7 years since they first met, a little boy whose life was miserable in hands of his caretakers, and a girl on the search for her way home. Friendship fostered in short time, little boy always saw her as a bratty-yet-kind-hearted big sister. Then, the girl has finally found her way back home. Now, before 5th year of magic school he attended started, he meet her again.