Kaketa Tsuki no Mercedes

Born again as a vampire, Mercedes Grunewald is the daughter of a nobleman and the concubine his household refuses to accept. She understands that her father will eventually name an heir other than her, leaving her mother, their aging maid, and herself with no protection and no means of support. Since anyone can venture into a dungeon, even a girl barely past toddlerhood, Mercedes begins her combat training absurdly early, counting on vampire blood to carry her strength further. Her previous life ended with nothing accomplished, and she intends this one to end differently.