Seiken no Blacksmith unfolds in the wake of the Valbanil War, a conflict that ended forty-four years earlier when the surviving nations declared peace and outlawed the demon contracts that had devastated the land. In that uneasy postwar world, inexperienced knight Cecily Cambell wants to honor her family’s legacy by protecting the people of the city with the sword she inherited from her father.
Her first test comes in the market, where a crazed swordsman attacks civilians and Cecily rushes in to restore order. She is quickly overwhelmed, and her weapon shatters, but a skilled stranger wielding a strange-looking sword steps in and saves the situation. Once the danger passes, Cecily goes to a local blacksmith to repair her family heirloom and learns that her rescuer, Luke Ainsworth, may be the only person capable of such intricate work. Determined to recover the sword that means so much to her, she seeks him out and is drawn deeper into his world.
Soon after, bandits attack a convoy headed for the city, and the assailants reveal themselves as something inhuman when an ice demon appears. Luke suspects the use of a demon contract and calls upon a sacred power to drive them back. All the while, a shadowy hooded figure watches from a distance, hinting that the peace after the war may be far more fragile than it seems.