Mercedes Grunewald is reborn as a vampire, the child of a noble father and the concubine he keeps at a distance. She has always known her father will name someone else as his heir, and she worries about what happens to her family when he does. Her mother has no useful skills, their maid is elderly, and Mercedes herself is only a small child. Dungeon crawling is work open to anyone, even someone her age, so she starts training while still of kindergarten age to support them. Being from a nation of vampires gives her the potential to grow strong. Having died unfulfilled in her previous life, she is set on finding something in the dungeons that will make her moon full. The story is a fantasy adventure that mixes action with family drama.