Dark Souls

They are twins, the two girls that most students refer to as "Dark Sisters". No one knows whether they are strong or especially gifted, they aren't popular, but no one ever tried to bully or duel them either.
There this this dull, cold, somehow scaring atmosphere around them.
No one dares to even speak to them, not even the teachers.
But one day, four transferees come to Màija Academy and things start to change.
Not only in the school, but in the world.

And they don't change for the better.