Testarotho

Testarotho (テスタロト) is a manga series by Kei Sanbe. It was serialized in Comic Dragon.

Plot
Capria has spent her life sheltered, and is brought into a world that is far from peaceful when she becomes part of the 'Testarotho.' The 'Testarotho' are fighting to convert all the people to one religion, in order unify everyone so there will be peace. Rebels arise to fight against them, but are soon brought down. Capria sees the way of both the Testarotho and the rebels, and is convinced both sides are fighting for what they truly believe in.