I've been looking for a story I first read nearly a decade ago. In it, this high-school girl summons a demon or something, which grants her magic powers. The demon grants her the power to trap and then transform someone into an animal for a portion of her remaining lifespan. She uses these powers to get revenge on a few other high-school girls who made her life a living hell. If I remember correctly, she turns one girl into a mouse, another girl into a snake, one into a chicken(I think?), and one into a cow. Seems like there was another one, as well. Anyway, afterward, she returns to the demon to complete the deal, and her takes the years she owes him, which ages her into an old woman. It was like 10 or 15 years per person, I think. Anyway, if anyone knows what story I'm talking about, I'd appreciate it!