Many years have actually passed given that mankind was driven to the verge of extinction by the sudden development of the unknown life types Gadoll. Those human beings that endured now dwell in a 3000m-high mobile citadel Deca-dence built to secure themselves from the Gadoll risk. Citizens of Deca-dence fall into 2 groups: Gears, warriors who battle the Gadoll daily, and also Vessels, those without the abilities to fight. Eventually, Natsume, a Vessel woman who dreams of coming to be an Equipment fulfills surly Kaburagi, an armor repairman of Deca-dence. This possibility meeting in between the relatively two revers, the lady with a favorable attitude that never ever quits on her desires as well as the rationalist that has quit on his, will at some point shake the future training course of this world.