Some alchemists made pacts with spirits, granting them the power to create drops of life—an ingredient that is vital to concocting potions of any kind. Mariela, one such alchemist, lives in a small cottage between Citadel City and the Fell Forest, where dangerous beasts lurked; she spends her peaceful days producing and selling potions.

One day, disaster strikes when a flood of monsters destroy Citadel City as well as the Kingdom of Endalsia—an incident later known as the Stampede. Out of desperation, the young alchemist hides in her cellar and freezes her body in time. However, a clumsy mistake puts her in an accidental slumber for two hundred years, only to wake up in a vastly different world: one where alchemists are all but extinct.

She is discovered by members of the Black Iron Freight Corps, who befriend her and escort her to Labyrinth City, the former Citadel City. Due to the Stampede, no new pact bearers have appeared in the past two hundred years, causing undue hardship for everyone. The arrival of Mariela sparks hope for a new era as her bubbly personality quickly wins people over. Thus begins the story of the alchemist who uses her unparalleled knowledge and skills to transform Labyrinth City, all the while lamenting the loss of her simple and inconspicuous lifestyle.