When My Shadow Grows Fangs

I was born without a shadow, until the night of my eighteenth birthday, two shadows suddenly appeared on the wall. One belongs to me, and the other is ferocious and twisted, tightly wrapped around my neck. It whispered: "Thank you for living for me for eighteen years, now it's time to pay back." In panic, I found a pawn shop that specializes in "abnormalities", but the boss sneered: "You were deceived, and that was your true soul, torn in two by the curse." The mirror behind me suddenly reflected my rotting corpse spots and a completely unfamiliar face.