In a world where consuming monster flesh is a deadly taboo, the lowest-ranked adventurers scrape by on the margins. Rude is an E-rank adventurer whose only innate skill is Status Abnormality Nullification, an ability considered nearly useless in combat. It does, however, allow him to survive the poisonous miasma of labyrinths long enough to gather medicinal herbs, a miserable task that earns him the mocking nickname the Grubby Forager or Miasma Scavenger. Desperate to change his circumstances, he joins a party of adventurers for a new dungeon expedition, hoping to prove his worth.

The expedition ends in betrayal. When the party encounters a powerful monster, his companions use Rude as a decoy and abandon him to die. Left for dead in the depths of the labyrinth, he is severely injured, his supplies are gone, and he faces a slow death from starvation. The only potential food source is the corpse of the monster he managed to kill. Despite the well-known risk that eating monster meat leads to death or transformation into a monster, Rude has no choice. He takes a bite and discovers the true nature of his power.

Instead of perishing, his unique skill prevents the corrupting effects of the flesh, allowing him to safely digest it and, more importantly, absorb the monster’s skills and abilities. The more he eats, the stronger he becomes, acquiring a diverse arsenal of powers that were previously out of his reach. This marks the beginning of his journey as the Monster Eater, an adventurer who grows not through traditional training, but through a forbidden and visceral form of consumption.

The narrative follows Rude’s rise from a despised outcast to a formidable adventurer, with his ultimate goal being to reach the prestigious S-rank. His path is shaped by the acquisition of new powers from each monster he defeats and consumes, forcing him to develop unique combat strategies. Key narrative arcs include his initial struggle for survival and discovery of his ability, his return to the adventurer’s guild to confront those who scorned him, and his encounters with other adventurers like Elyssia, who becomes a significant companion. The series is a dark fantasy adventure that combines survival, relentless progression, and the moral and physical consequences of breaking the world’s most fundamental rule to achieve strength.