In a world where exploring treacherous dungeons is a way of life, Rudd is an E-rank adventurer with a seemingly useless unique skill: Status Ailment Nullification. This ability allows him to resist the poisonous miasma found in certain labyrinths, making him useful only for gathering medicinal herbs. His lack of combat prowess earns him the scornful nickname Miasma Scavenger, and he struggles to find any party that will take him seriously. Desperate to change his fortunes, Rudd joins a group of adventurers as a porter for a new dungeon expedition. However, his hopes are brutally crushed when a deadly monster appears, and his companions betray him, using him as bait to cover their escape and leaving him for dead.

Wounded, alone, and with his supplies destroyed, Rudd faces a slow and certain death in the depths of the labyrinth. On the verge of perishing, he makes a desperate and forbidden choice: to consume the flesh of a monster he managed to slay. This taboo act triggers an unexpected and profound change. Rudd discovers that by devouring monsters, he can permanently absorb their powers, skills, and physical traits, transforming his worthless immunity skill into the foundation of an unparalleled ability to grow stronger. What began as a final act of survival becomes the start of a new legend.

The protagonist, Rudd, is a young man who has been an outcast, looked down upon by the adventurer's guild and his peers. His initial weakness and desperation fuel his determination to rise from the bottom. A key figure in his journey is Elyssia, an adventurer who becomes associated with Rudd as his unique power begins to manifest and draw attention. The story follows Rudd as he navigates a fantasy world dominated by labyrinth exploration, powerful monsters, and guild politics, where trust is scarce and betrayal is a constant threat. The narrative arc traces his transformation from a pitied scavenger to a formidable force, with each monster he defeats and consumes adding to his repertoire of abilities, all while the circumstances of his initial betrayal and the broader implications of his power begin to unfold.