In a world where everyone is born with a magical affinity, Flum Apricot’s unique power appears to be a curse rather than a gift. Chosen by the god Origin to join the hero’s party on a quest to defeat the Demon King, Flum’s ability, called Reversal, leaves her with zero stats and makes her weaker than an ordinary village girl. Deemed completely useless by her companions, she endures constant bullying from the party’s genius sage, Jean Inteige. His disdain for her culminates in a brutal betrayal: Jean sells Flum into black market slavery simply to be rid of her.

Branded and thrown into a dark dungeon, Flum’s situation grows even more dire when a slave trader decides to feed her to a pack of ghouls for his own entertainment. It is in this moment of utter desperation that she discovers the true nature of her Reversal ability. Contrary to all belief, her power does not weaken her but instead reverses the effect of any curse placed upon her. The stronger the curse, the more powerful she becomes. When she grasps an epic-level cursed sword that should melt her flesh, the effect is reversed, healing her wounds and granting her immense strength. Using this newfound power, Flum fights her way through the ghouls and kills the slave trader, escaping the dungeon with a fellow captive, a quiet and heavily bandaged girl named Milkit.

The series follows Flum as she struggles to build a new life as an adventurer in the royal capital while caring for Milkit, who was born into slavery and struggles to understand her new freedom. Their relationship forms the emotional core of the story, gradually developing into a close bond as Flum vows to protect Milkit and give her a happy, ordinary life. However, peace is hard to find. Flum is branded as a fugitive slave, forcing her to take on dangerous and often suspicious quests just to survive. She soon uncovers dark secrets lurking beneath the surface of her world, including the church’s questionable motives for suppressing herbalism and the strange behavior of the Demon King’s forces, who seem reluctant to kill humans. Meanwhile, the hero’s party left behind begins to crumble without Flum’s quiet but essential support, revealing that her presence was far more vital to their success than anyone realized.

As Flum and Milkit navigate this grim and violent world, they encounter a cast of allies and enemies, including the adventurer Eterna Rinebow and the corrupt guild official Dein Phineas, who serves as a dark mirror to Flum’s own struggles. The narrative follows Flum’s bloody quest not just for revenge against Jean, but for the right to live peacefully with the person she loves, even as her cursed power forces her to confront ever-greater horrors.