A protagonist reincarnated as a vampire. Her family is noble, but her mother is a concubine, and her treatment is far from good. Isolated in a dilapidated mansion with her mother, she knows she'll eventually be discarded. Currently, she maintains a living due to inheritance rights, but the family will eventually pass to the legitimate wife's child. This doesn't bother her, but she must prepare to survive independently when the time comes. Fortunately, this world has dungeons and the job of a Seeker. Her goal? Dungeon conquest. She'll delve into dungeons, earn money, grow stronger, gather allies, and delve further. Remembering her previous life, where she lived without purpose, died without fulfillment, Mercedes Grunewald firmly resolves: "Because it's my second chance, I want to live without regrets, and die laughing." This is the story of a waning moon becoming full, and ending her life with a laugh.