Chaika: The Coffin Princess Vol. 1 (manga)

Five years of inconceivable peace after two hundred years of war has left erstwhile soldier Tooru Acura without a job or meaning in life–until he saves a mysterious sorceress with a coffin on her back. But when the coffin-wielding, silver-haired Chaika Trabant hires Tooru and his sister, Akari, to accompany her on a death-defying journey, Tooru’s life of mind-numbing, meaningless peace is about to end!