Broken Wings: A Blue Exorcist Fan fiction

Set four years after Rin Okumura graduates from True Cross Academy. Kyokumi Michizaki, known better to the Heavens as Karan the Flame, has abandoned Heaven's legions. She escaped to Earth. But, four years later, Heaven plans an assault on Earth. The underworld is plotting a similar attack. And Earth is mostly ignorant. Will there be any true survivors?
(Note: I did not read the Blue Exorcist manga so I'm sorry if I get anything wrong.)