Blue Mistral tells the story of how sky-dragon slayer Wendy Marvell met her lifelong friend Carla, and the adventures they had together before joining the Fairy Tail guild. Wendy Marvell was raised by the dragon Grandeeny to practice the wind-based sky dragon slayer magic. Her only friend is Carla, a magical cat exiled from her home. When Grandeeny suddenly disappears, Wendy and Carla must face the perils of the Dragon Valley alone.