After Dying, I Became the Moon Goddess

Violet's life seems to have a countdown hanging above her head, and her family decides the answer is to offer up the heroine, who is not truly their daughter, so that Violet's remaining wishes can be granted. The heroine is caught in a household where affection has always been rationed by blood, and the sacrifice is treated as a simple duty. Her struggle to survive a family that will spend her to keep its real child alive forms the heart of the story.