Okumura's sister (blue exorcist fanfic)

Kurai Tanaka is the daughter of Satan. She has been living in Gahenna all of her life until Mephisto suddenly offers for her to come to Assiah and join his elite academy.
Ecstatic, she takes up his offer and quickly leaves Gahenna.
However, how will the daughter of Satan take to joining the cram school for exorcists, the people who've been trying to kill her family for hundreds of years? And discovering that she's had two twin brothers all along?
Meanwhile, Mephisto is scheming behind Kurai's back and she intends to find out what he's up to.
Even Assiah can be a strange place. You don't know what could happen...