This world consists of two dimensions joined as one, like a mirror. The first is the world in which the humans live, Assiah. The other is the world of demons, Gehenna. Ordinarily, travel between the two, and indeed any kind of contact between the two, is impossible. However the demons can pass over into this world by possessing anything that exist within it. Satan the god of demons, but there's one thing that he doesn't have, and that's a substance in the human world that is powerful enough to contain him!! For that purpose he created Rin, his son from a human woman, but will his son agree to his plans? Or will he become something else...? An exorcist?

[Source: MyAnimeList]

Ura Ex, extra short anime included in Blu-ray and the DVD releases of Ao no Exorcist.

Feeling slighted by Rin, Kuro goes on the hunt for a new master, but can he find anyone who can truly replace Rin?

A collaboration between Blue Exorcist and Kakko Kawaii Sengen.

The atmosphere in True Cross Academy is lively and boisterous in the days leading up to the grand festival held once every 11 years. During this time, Okumura Rin is entrusted with the responsibility of suppressing the berserk Phantom Train. In the midst of his mission, he meets a devil whose appearance is that of a young boy.

[Source: official site]

Assiah, the realm of humans, and Gehenna, the realm of demons. 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 exorcise such demons—the exorcists.

Rin Okumura kept the fact that he was Satan’s offspring a secret from everyone and decided to become an exorcist. He began his training at True Cross Academy but following the incidents involving Amaimon’s raid, his lineage became apparent. Fearing his true nature and the blue flames marking his connection to Gehenna, Rin’s classmates all distanced themselves from him. Meanwhile, the academy was on high alert when they realized that the “Left Eye of the Impure King” had been stolen! What lies ahead for Rin and his classmates?

[Source: Aniplex of America]

Unaired episodes bundled with the 19th and 20th volumes of the manga.

Rin and his friends successfully defeated the Impure King after his revival in Kyoto and have returned to their daily lives at True Cross Academy.

However, the Knights of the True Cross begin receiving an increasing number of consultations about demons as a wave of strange events begins to spread across the world. Meanwhile, Rin and the other Exwires work to solve the mysterious phenomenon plaguing the school.

But as the True Cross Academy Festival is in full swing, Lucifer, the King of Light and Commander-in-Chief of the Illuminati, suddenly appears.

Lucifer declares war on the Knights of the True Cross – to resurrect the demon god Satan and rejoin the realm of humans, Assiah, and the realm of demons, Gehenna, as one.

And to do so, he states that Izumo is necessary for a certain “plan".

[Source: official English website]

Brothers Rin and Yukio head to Lake Towada in Aomori to search for Shura, who had suddenly disappeared.

There, they find Shura’s birthplace – the place where Shiro became her guardian. As their search continues, Rin and Yukio discover the fate that awaits Shura.

Meanwhile, Lightning, one of the Arch Knights, arrives at the Japan Branch of the Knights of the True Cross and begins his investigation into the Illuminati.

Lightning deduces that everything began on the “Blue Night,” as he gradually steps into the dark side of the Knights of the True Cross….

[Source: Aniplex USA]

Yukio parts ways with Rin and makes his way to the Illuminati.

In order to face Yukio, who is seeking strength and the truth, Rin decides that he must learn the secret of their birth. With Mephisto’s guidance, he embarks on a journey to the past.

Rin traces the footsteps of their adoptive father, Shiro Fujimoto, and birth mother, Yuri Egin. But the path they took in life was harsher than Rin could have ever imagined....

Why were children born between the Demon God Satan and a human?

What was the Blue Night?

And when Rin learns everything, what will be his answer...?

[Source: Aniplex USA]