Chaika: The Coffin Princess(2011)

Hitsugi no Chaika

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

(Source: Yen Press)