Kanata no Togabito ga Tatakau Riyuu

From AQUA Scans:

A group of scattered people who’ve lived sin-filled lives head off to battle once again after their deaths; each one harboring their own reason to fight. When the fighting is finished and their sins have been atoned for, their souls will be returned to them. Kanata no Togabito ga Tatakau Riyuu is an epic fantasy from a long anticipated new author, and the story of those who fight on and are burdened by the sins from their past.