In the world of Unchained, cities are separated by vast expanses of open sky. Airships have become the primary mode of travel in the modern age, transporting goods and people on a regular basis. Due to the extreme costs and safety issues of relying on these unstable machines, shipping has attracted adventurers and pirates alike to this lucrative and dangerous business. As captain of the Alethea, Mira has inherited her father's shipping business and airship support robot, and now she struggles to make ends meet while trying to climb from poverty to affluence; though she never loses sight of her childhood dream- to fly for as long as it takes to find the edge of the world.