The Heroine's Treasure

At the end of the story, the Demon Lord, who was in the form of a dragon, was killed by the heroine. There was only one step left to let the world return to peace: to seal the soul of the Demon Lord. If the seal were to fail, then the returning Demon Lord would summon the fire of hell to burn the entire world. Only when the heroine would offer her most cherished treasure of her life, the seal would be finally comp...