Aniplex announced the second season of Ao no Exorcist/The Blue Exorcist! Rin Okumura and his gang returns for a second season after 5 years. Half of the first season's episode was an "anime-original" which meant that it didn't follow the manga's story for various reasons. The second season is to adapt the Impure King Arc of the manga.
The first season of the anime aired in 2011 and followed by an anime film called "Ao no Exorcist Gekijouban" in 2012. The cast is still the same but the staff had been changed. Most noteably the Director, Koichi Hatsumi had replaced Tensai Okamura, and the Writer Toshiya Oono will replace Ryota Yamaguchi. Animation studio A-1 Pictures will still produce the show.
A rundown of the second season of The Blue Exorcist from Aniplex USA:
"The human realm Assiah, and the demon realm Gehenna. Normally, these two dimensions would never intersect, but having possessed all material substances, the demons are now intruding on the material world. But among the human race, there are those who can fight the demons known as the Exorcists.
Born as the Son of Satan, Rin Okumura decides to hide his origins, and become an exorcist. He enrolls at the Exorcism Cram School, a training institute for exorcists located on the True Cross Academy grounds. But, his cover is blown during an attack by Amaimon, the King of Earth, and he is revealed to be the son of Satan. Terrified of Satan's blue flames, his friends start to distance themselves from Rin...
It is then that someone steals the Left Eye of the Impure King, sealed away in the deepest part of the academy, and Rin and the others find themselves embroiled in an unexpected crisis..."
Here is the trailer for the second season of Ao no Exorcist/The Blue Exorcist
The Anime is set to start airing on January 2017