Alcia is a world governed by "Count": numbers engraved on a person's body, representing any number related to their life. These Counts determine a person's social status and power in Alcia. If a Count reaches zero, the person is sent to the Abyss, a place rumored to be worse than death. Hina, a traveler whose Count is based on the distance she traveled, witnessed her mother get dragged down into the Abyss. Determined to fulfill her mother's last wishes, she sets off on a journey in search of the legendary Aces—heroes of the war that happened three hundred years ago, bearing a white star next to their Count. While wandering around, Hina encounters Licht Bach, a mysterious masked man with negative Count, and Nana, the owner of a tavern. In the midst of having a good time, Hina is tricked into a battle with a military soldier. However, despite his negative count, Licht rescues Hina and reveals that he has another count, one with a white star, one of a legendary Ace. Plunderer follows the journey of Hina and other inhabitants of Alcia as they discover the truth about their world, the Abyss, and the legendary Aces. In a post-apocalyptic world dominated by the so-called "Numbers," each human will have their identity branded with their own "Count," which could define any number related to their life. May it be one's walked distance or amount of compliments given to them by others, this Count could lead them to the abyss when it has dropped to zero.