Deca-Dence S01E01 - Ignition

In the distant future, humans have been pushed to the verge of extinction by the invasion of mysterious life-forms called the Gadoll, and were now forced to live inside the moving fortress Deca-dence as they desperately kept up resistance. Natsume, a girl who grew up with a dream of becoming a fighter, is assigned to work under the hard-nosed but apathetic armor-repairman Kaburagi, and finds herself spending her days swamped with endless routines of cleaning work. But one day, Natsume gets herself caught up in a battle with the Gadoll while on work, and what she witnesses is the sight of Kaburagi taking down one Gadoll soldier after another.