Aomori Hachirotaro arc

The Aomori Hachirotaro arc (青森・八郎太郎) is the eighth arc of the Blue Exorcist series.

Being called away from their duties, the Okumura twins are sent on a mission to find Shura Kirigakure.

Searching for Shura
Mephisto Pheles orders the twins to begin their search for Shura in Aomori, as not only is this Shura's home prefecture, it is also where her GPS last recorded her whereabouts. Yukio objects to bringing Rin with him, but Mephisto insists, saying that he has been doing dangerous training and now is the chance to relax and blow off some steam.

Heading out to Aomori, the twins search in vain until a taxi driver informs them that he gave Shura a lift to Lake Towada The pair check into a hotel near the lake, where the elderly innkeeper mistakes the pair for a gay couple. The next morning, after losing his temper with the innkeeper, Yukio forcefully shows her the picture of Shura only to find out that she had spent the night at the hotel.

While the twins search for her, Shura confronts a mysterious figure she addresses as Hachiro, who informs her that the Illuminati have slain a long lived comrade. When Shura offers her protection, Hachiro refuses, instead insisting that Shura fulfill her promise. Shura refuses, and Hachiro threatens to take her Fang. When that fails to elicit the desired response, Hachiro attacks. Noticing someone approaching, he leaves Shura in the snow, stating that he will not let her die yet. Arriving on the scene, the twins find Shura and rush her back to the hotel. When she comes to, she informs the two that she will die soon.

History of the Kirigakure
While recuperating, Shura explains that she is in a blood contract with Hachirotaro Okami. When questioned why she would enter into a contract with such a creature, she explains that it was not her, but her ancestor, Tatsuko Kirigakure.

Fleeing the Iga ninja to start her own style, Tatsuko fled into the north where she encountered Hachiro. Crossing swords with the demon, she was easily defeated, but her tenacity to survive enraptured him, prompting the Hydra to make a deal with Tatsuko. He would grant Tatsuko and her descendants his power and the use of the demon sword, Fang, but in exchange, each successive generation would look like Tatsuko and die by the age of thirty, allowing Hachiro to admire her beauty forever.

Having resigned herself to death, Shura's only method to resist the curse was to refuse to bear a child as she didn't believe there was another method to deal with the situation. After leaving her to rest, it is not long before Rin senses a presence nearby and the pair rush back to find Shura missing.

Shura dreams about her past while unconscious. Having grown up without knowing her mother, she spent her time in the wilderness training with Hachiro, or heading into town to test her sword. Becoming known as a Baba Yaga, the exorcist, Shiro Fujimoto is dispatched to deal with her. When Hachiro attacks, Shiro easily injures the immortal hydra, causing Shura to become infatuated with him. Being forced into taking her with him, Shiro writes a false report on the incident and gives Shura her first name, taking it from her likeness to an Ashura.

Battling Hachiro
Shura awakens to find herself in front of the Towada Shrine. Hachiro using his powers to control her, he declares that she will bear a child. When Rin and Yukio appear to intervene, Rin is sent flying, but Yukio is also taken captive. Pleased that he now has a human male to fulfill the necessary role, Hachiro prepares to force Shura to bear a child.

However, before he can carry out his plan, Hachiro is burnt by Rin's flames, causing his hypnotic powers to falter. Rin engages Hachiro in battle, but it seems that even his blue flames cannot overcome Hachiro's ability to regenerate. Faced with this predicament, Yukio offers to make a contract with Hachiro. Wishing for the demon sword and regeneration, he offers to convince Shura to concieve a child, but when Rin objects, Yukio shoots him. Agreeing to Yukio's terms, Hachiro removes the contract mark from Shura and prepares to transfer it to Yukio. Before he can transfer the contract however, Rin stabs him from behind, complaining about Yukio once again using nutrient bullets to decieve him. Using Satan Campfire to incinerate Hachiro, the trio believe their work is done, but it proves ineffective, Hachiro taking on his true form in order to finish them off.

Yukio warns Rin of Hachiro's hypnotic gaze, but despite this, Rin still falls victim to it. Aiming to shoot out Hachiro's eye, Yukio's attack is pre-empted by Renzo Shima. As the others attempt to co-ordinate a strategy, Shura convinces Hachiro to seal himself away on the lake bottom with her. Resigning herself once more to death, Shura sinks into the lake with Hachiro, but as she does so, remembers a time when Shiro lectured her about living a good life. Questioning whether or not she could live such a life, a bright light breaks through the frozen surface of the lake as Rin and Yukio attack with Rin's Satan Bomb Campfire.

Inspired by the twins' continued efforts, Shura escapes Hachiro's grip and attempts to escape, but Hachiro manages to capture her once more, breaking through the surface of the lake. Capturing Rin and Yukio, Hachiro prepares to kill them, but an infuriated Shura cuts herself and the others free and declares that she no longer needs Hachiro. Freed from Hachiro's grip, Rin once again starts to burn the Hydra. Burning away most of Hachiro's body, he is reduced to a simple serpent with next to none of his former of intellect.

Cleaning Up
Shima meets up with the others after being blown away in the battle with Hachirotaro. Asking what became of the demon, Rin tells him that he got away. Shura sighs in relief, stating that she is a brand new person. Thanking Rin and Yukio for helping free her from Hachirotaro's curse.

The reinforcements finally arrive to clean up and search for Hachirotaro. After patching up Yukio's injuries, Shima talks to him about his plan to obtain Hachiro's powers and suggests that his teacher join the Illuminati. Taking off to help with the search party, Shima sneaks away on his own and captures the miniscule Hachirotaro. Meeting up with an Illuminati helicopter, he hands the demon off to Saburota Todo. Todo advises Shima that winning Yukio over to their cause could improve his standing within the Illuminati and to keep trying to convince him.

At True Cross General Hospital, Yukio reflects on the words Lucifer said to him at the Far East Laboratory and states to himself that he needs a broader vision.