Anime-Exclusive arc

The Anime-Exclusive arc is the third arc of the Ao no Exorcist anime series and the final arc of the original anime production.

Gufu
Rin Okumura and Izumo Kamiki are attacked suddenly by an unknown demon in the Cram School, but are saved by the timely intervention of Yukio Okumura. Meeting with Mephisto Pheles, the exwires are informed that a demon called Gufu had somehow infiltrated the academy and that they were to inspect the barrier.

It transpires that Konekomaru Miwa had come in contact with the demon and was on the verge of becoming possessed. Rin encounters Konekomaru in the classroom and attacks the Gufu, but the others don't believe his intent and fight Rin.

Meanwhile, Shura Kirigakure and Kaoru Tsubaki discover the door leading beyond the barrier that the Gufu likely used to infiltrate the school.

After hearing about the fight with Rin, Konekomaru becomes fully possessed by the Gufu and hunts down Rin in order to kill him. After managing to separate Konekomaru from Gufu, Rin destroys the demon with his blue flames.

The ordeal makes Konekomaru want to give up on his pursuit of becoming an exorcist, but before he can leave, Rin shows up and convinces him to stay.

A Day When Nothing Happens
The episode opens with Yukio doing his weekly test on his blood, only to find that it reacts unexpectedly with blue sparks.

At the Cram School, Renzo Shima interrogates Shiemi Moriyama and Izumo about their birthdays to give them fortunes. However, after Izumo blows him off, Shiemi realises that Izumo's birthday is coming up. The group decide to throw a surprise birthday party for her. Ryuji Suguro deals out the responsibilities, leaving Shima to get the present, while Rin and Konekomaru deal with the cake.

Shima consults Noriko Paku as to what Izumo might like, leading her to believe the two might be dating. After finding the other exwires avoiding her, Izumo goes to meet with Paku and tells her Shima isn't right for her.

Rin shows the others a giant christmas cake, but is stumped as to why nobody else likes it. The others have to inform him that christmas and birthday cakes are different, a fact he and Yukio were unaware of due to their birthday being December Twenty-Seventh.

The next day, Izumo stalks Shima and Paku, thinking they are on a date, however, after letting her imagination run away with her, she confronts the pair and finds out the truth about the surprise party.

Scolding the other exwires, she complains that they skipped several other people's birthdays, so they end up turning it into a group birthday. Yukio watches on when Shiemi approaches him, and he reflects on the fact that he and Rin did not know their real birthday and that their father always evaded the topic. The episode ends with Yukio recieving a phonecall that the Southern Cross Boys' Monastery had been attacked.

The Masked Man
Rin and Yukio arrive at the monastery to find that all the monks had been attacked and encased in a web-like substance. A message scrawled on the wall in Polish stated the perpetrator would not forgive those related to Satan. Rin takes off only to be confronted by a masked figure. Yukio and Shura soon arrive, prompting the figure to flee. When they attempt to track them, Yukio arrives at a clock tower where he meets Igor Neuhaus. Yukio accuses him, but Neuhaus denies any involvement, fleeing before Yukio can stop him. They later track Neuhaus into the sewers, but Susumu Yunokawa is ambushed and engulfed in web, forcing them to break off their pursuit.

The masked man attacks the boys' dormitory, taking Ryuji, Renzo and Konekomaru hostage in order to lure out the son of Satan. Mephisto attempts to intervene, but is taken into custody by Arthur A. Angel before he can carry out his attack. Yukio attempts to battle the masked man, but is ensnared. When Rin and Shura break in, the battle takes a turn when it is shown that Rin's blue flames can burn away the web. The masked figure turns out to be a woman, but when she attempts to flee, Neuhaus interferes. Shura captures him while the woman, revealed to be his wife, Michelle, escapes.

While Rin burns the webbed up victims at the monastery, Yukio is approached by Bourguignon, stating there is someone he wants Yukio to meet. He is taken to a train where he meets with his grandfather, Ernst Frederik Egin.

Shiemi, while listening to a radio report on events at the dormitory, hears a noise and runs outside to find Michelle Neuhaus unconscious in the garden. Unable to move her, multiple baby Greenmen appear in order to help her.

Meanwhile, Yukio talks with Ernst about their mother, Yuri Egin. He tells Yukio that he had been imprisoned for fifteen years following the Blue Night and that he had lost everything, his standing, his face and his daughter, stating that the Grigori had ordered Yuri executed as a witch for carrying the spawn of Satan.

Rin returns to the Japanese branch of the True Cross Order in order to listen in on Neuhaus' interrogation. When he states that he was not the one to resurrect Michelle, he explains that while he had preserved her body, someone else had transformed her into an Anti-Soul, allowing a demon to possess her, but he could not bring himself to kill her a second time. Bourguinon and forces from the Order soon arrived at his lab and burnt it to the ground, attempting to take him and Michelle into custody, but he fought them off and escaped. Michelle, becoming increasingly unstable due to remembering her death at the hands of Satan, she resolved to get revenge on anyone involved with Satan. Rin decides to try and track her down.

Shiemi calls Rin for help and he arrives in the secret garden that once belonged to Shiemi's Grandmother. He confronts Michelle, but before the situation can escalate, she collapses, her body continuing to rapidly weaken due to being an animated corpse. Heading back outside, Rin comes face to face with Angel and a unit of exorcists. Rin defends Neuhaus and his wife from the exorcists, but when one of them attempts to shoot Rin, Michelle takes the bullet for him. With her life slipping away, Neuhaus goes to leave with Michelle in his arms, the baby Greenmen defending them from the exorcists. Before they can pursue the pair, the bells across the Academy start to ring, signalling a recall to the Vatican Main Office.

Operation: Jacob's Ladder
After the incident with the masked man, the academy is closed, Mephisto taking the blame for the incident and being forced to resign according to public reckoning. This leaves students unable to even retrieve their belongings. Izumo reveals that the situation is even more dire than it appears, with the higher ups in the Vatican being removed along with the pope, and Ernst taking his place as head of both the Church and the Order.

In the Cram School, it is revealed that Yukio has been installed as the new head of the Japan Branch of the Order and as the new Paladin. In an announcement made by Ernst, he declares the beginning of Operation: Jacob's Ladder in order to eradicate demon kind once and for all. All exorcists, including the exwires, are given special weapons for the mission and sent into battle. Yukio reflects on the true nature of the mission, gathering enough demon blood to create an artificial Gehenna Gate in order to destroy Gehenna using a powerful bomb called the Messiah. Ernst having told him that by destroying Gehenna, both Rin and he could become entirely human, Yukio agrees to go along with the plan, despite its callousness.

After getting into a fight with Rin, Yukio has his brother detained and brought to the Vatican Main Office. Finding himself imprisoned along with Mephisto, Mephisto explains to Rin that he was imprisoned because he once ran the Research Lab for Artificial Life before transforming into his dog form and leaving. Rin is then taken to the roof of True Cross Academy to be executed, his blood added to that collected by the blood-sucking weapons to complete the Gehenna Gate. However, when Yukio witnesses this, he offers to use his own blood in place of Rin's.

Upon adding his own blood to the ritual, the Gehenna Gate begins to form, but at the same time, Yukio's body is possessed by Satan. The Messiah is launched, dropping into the gate and creating a massive pillar of light, but ultimately proves ineffective at destroying Gehenna. The Gehenna Gate begins expelling demons in the thousands, pulling Ernst into it. Yukio hears the voice of Satan in his mind, the God of Gehenna revealing the truth of his mother's death to him.

Many years ago, Yuri lived in the forest, living in harmony with the demons that inhabited the area. When the Order sends Shiro Fujimoto to retrieve her, she reveals that her body has been possessed by Satan and that a year ago, her and a team of exorcists had been sent to investigate a case, only for the majority of her team to die, leaving only her alive. Tracking down Satan, she communicated with the demon, attempting to make him understand the nature of life in Assiah through her. Not knowing what the concept of life means, Yuri offers to nuture one with Satan, leading to her becoming pregnant with the Okumura twins.

When word of this reaches her father, Ernst, he demands she abort the child in spite of Church doctrine, and when Yuri refuses, she is sentenced to death as a witch. Satan, in an attempt to save Yuri, tries to find a vessel capable of containing him, this leading to the infamous Blue Night. Taking hold of Ernst himself, Satan manages to free Yuri, who flees back to the forest. Shiro and Mephisto are sent to pursue her, but upon discovering the dying Yuri and her children, Shiro cannot bring himself to kill the children and instead takes them in as his own. Mephisto seals Rin's power in Kurikara and goes to report that the spawn of Satan is indeed dead. After hearing the story, Yukio demands to know if Ernst was the one who ordered his mother killed and when his grandfather confirms it, Yukio is overcome with anger, allowing Satan to take control of his body properly.

Showdown with Satan
As demons continue to spew forth from the Gehenna Gate, the exwires confront Satan. He reveals his intention that, with Yukio's body as a container, and the artificial Gehenna Gate, he can bring Assiah and Gehenna together into a new world. When the exwires attempt to battle him, they are easily dispatched, none of them proving any sort of match against Satan. Before he can kill them however, Shura intercepts Satan's attack and allows the team a chance to escape.

Retreating from the execution ground, they form a plan to destroy the Gehenna Gate, with Shura baiting Satan while Rin attacks the gate. Meanwhile, the other exwires set about evacuating civilians to the Japan Branch office.

The battle with Satan resumes, but the strategy falls apart as Shura is defeated and Shiemi attempts to reach out to Yukio. As Satan prepares to kill her, Rin breaks cover to address Yukio as well, his voice breaking through to Yukio and allowing him to throw off Satan's control. Yukio, in a desperate attempt to stop Satan, attempts to kill himself, but Rin punches him, bringing him to his senses as Satan flees his body. However, he then takes control of the Gehenna Gate directly.

Centuries ago, Mephisto is seen making a deal for the soul of an apparent scientist. Back in the modern day, Rin and Yukio continue to battle waves of demons from the Gehenna Gate. Arthur A. Angel joins the fray, rescuing Shura and Shiemi from an attack, but as he assure them he can handle the situation himself, it proves too much, neither his, nor Rin's attacks proving effective. After a disasterous attack from the gate, Yukio, Rin and Kuro plan to strike once more.

With demons breaking into the Japan Branch, Terufusa Adachi states that they need only hold out until morning for the demons to become weakened. As Shima laments this, pointing out that the Sun only just went down, Konekomaru has an idea. Using the direct link to the Vatican main office, where it is still day time, he suggests luring them into the city, but Ryuji comes up with another solution. Setting up mirrors along the path, the exorcists direct sunlight from the Vatican directly to True Cross Academy. With the demons guarding the gate weakened and temporarily blinded, Rin and Yukio push their assault, but are knocked from Kuro's back. Falling through the air, Yukio grabs Kurikara, unsheathing it. Grabbing Rin's hand, the pair are engulfed in blue flames. Together, they create a giant flaming bird that flies into the Gehenna Gate, destroying it with a single blow.

With the gate destroyed, Mephisto reflects on the wager he made all that time ago and remarks that he now understands the feelings of the man he made it with at the time of his death.

A month later, things return to relative normality, Mephisto being reinstated as director of the academy, classes beginning once more and Yukio being demoted to his previous position. Being given a key by the director, Yukio and Rin travel to the forest where they were born and visit their mother's grave.

The episode ends when, while setting up a road block to stop a Ghost Rider, Yukio and Shura are interrupted by Rin interfering in their mission.

Trivia

 * While never confirmed in the manga, this arc seemed to imply that Mephisto Pheles is in fact the Mephistopheles from the story of Dr. Faust, and that the man he made the bargain with, is the titular doctor whom was granted immortality.
 * Despite being an Anime-Exclusive arc, Satan's plan for a unified world and the creation of an artificial Gehenna Gate mirror the later actions and motivations of his son, Lucifer's organisation, the Illuminati.