Hitsugi no Chaika

Toru Acura, an incredibly lazy man with some hidden talents, has been forced by his sister Akari to actually go outside and search for work. However, he is in for a big surprise when he meets the girl who carries a coffin on the back named Chaika Trabant in the forest, and they are suddenly attacked by a monster! How will they survive? Who is this mysterious girl, and why is she being targeted?