By the sudden invasion of the Ishikari Empire, all the neighboring countries were destroyed. A year after that the people in the colonized countries were oppressed and put to forced labor. Cardinal Sepia Arush, the captain of the former secretary of the state, organized anti-empire resistant movement. The organization got name Sepia, and it consists only of women mages who dance at the battlefields to return the lost homeland.

[From vndbreview]