Gin'iro no Kami no Arisa

As a child, the eponymous heroine is betrayed by three jealous friends who throw her into a pit and leave her to die. But Arisa perserveres: She trains herself to be smarter, faster, and more beautiful than any of them and returns for revenge. Years of living underground have left her with the silver hair of the title, so her victims can't be sure whether the resemblance is real or only the product their guilty consciences...