In the world of Alcia, people are marked with "Count" numbers etched into their bodies, representing any numerical aspect of their lives. These Counts define a person's social standing and influence. When a Count reaches zero, the individual is sent to the Abyss—a place said to be worse than death. Hina, a traveler whose Count is determined by the distance she has traveled, saw her mother dragged into the Abyss. Driven by her mother's final wishes, she begins a journey to find the legendary Aces—war heroes from three hundred years ago who each bear a white star beside their Count. While traveling, Hina meets Licht Bach, a masked figure with a negative Count, and Nana, the tavern's owner. During a moment of relaxation, she is tricked into fighting a military soldier. Yet, despite his negative Count, Licht intervenes and saves her, revealing that he possesses another Count—one marked with a white star, identifying him as one of the legendary Aces. Plunderer follows Hina and other residents of Alcia as they uncover the truth about their world, the nature of the Abyss, and the real stories behind the legendary Aces.