Igor has brown, long hair, as well as pale skin. He wears an eye-patch over his left eye, which was burned out during the Blue Night when he was possessed by Satan. He wears the standard Exorcist uniform, a full black coat with black pants. He also keeps bandages on his fingers and arms, which contain summoning tattoos underneath.
Due to being possessed by Satan during the Blue Night, Igor lost his left eye to Satan's blue flames, as well as his family when he killed them under Satan's influence. Because of this, he hates Satan immensely, as well as any Demons related to Satan. He seems to believe that as Satan's son, Rin can only be evil at heart and must be destroyed no matter what. Ironically, he is extremely loyal to Mephisto, another one of Satan's sons, and was able to put aside his hatred for Rin and stop attacking him when Mephisto asked him to.
During the time of the Blue Night, he was possessed by Satan for a moment and used to kill his own family with his hand. Unlike other victims of Satan's possessions, he survived because only his left eye was possessed. This has caused him to despise anything related to Satan, including Rin.
True Cross Academy arc
During the Exwire exam, he is the one that summons a Naberius to attack the candidates. However, Neuhaus intentionally directs his Demon to attack in order to see his blue flames. After the exam, he has a verbal confrontation with Yukio where he justifies his actions, saying that he never intended to kill Rin, and was only operating as ordered.
The next evening, Neuhaus attempts to assassinate a sleeping Rin. However, the plot is foiled by Yukio and Shiemi, who had moved a still-sleeping Rin into another room. Igor attempts to flee to the roof top and summons a host of minor Demons to distract the gun-wielding Exorcist. On the roof, the Tamer distracts Yukio with more minor Demons and prepares a summoning circle to summon an enormous, upper-class Naberius. Rin appears to assist Yukio, and the two team up to subdue the upper-class Exorcist.
Refusing to lose, Neuhaus continues to attack Rin. The half-Demon accepts the blow, but demands that Igor attack him without involving bystanders. Shocked, the elder Exorcist departs, but not before telling the Okumura brothers that there many people who want the son of Satan dead, especially among Exorcists.
It is later revealed that Neuhaus was secretly following the orders of Mephisto Pheles in an attempt to further awaken Rin's demonic powers. Some time after this he departs from the cram school, and his role is taken by Shura.
Exorcist Exam arc
He is mentioned during a meeting between Mephisto, the Grigori and the Arc Knights, where Mephisto reveals his location is unknown.
Blue Night Investigation arc
Lewin and Bon run into him in the abandoned cram school.
Meister & Abilities
Tamer: As an Upper First Class level Tamer, Igor is able to both summon and control high-level Demons. He has been shown to summon two types of Demons: demonic hands, summoned through tattoos on his arms, that latch onto opponents to hold them down. His most commonly seen Demon is the Naberius, a Demon that was capable of holding back both Yukio and Rin Okumura for a time. As a upper-level tamer, it is implied that Igor possesses incredibly high willpower and spiritual fortitude. Additionally, he has great stamina and endurance, able to shed large volumes of blood to summon masses of Demons and continue to fight. This is made more impressive by the fact that he was able to draw an exceptionally complex summoning circle in seconds, implying that he is able to maintain focus despite injury.
Capable Melee Combatant: He has been shown using a huge drafting compass for a sword and has displayed considerable skill with it.
Spectral Awareness: As he is an Exorcist, Igor had to perform the Mashō Rite, thereby allowing him to see Demons.
- He has ten spare eye-patches with the same design.
- His pastimes and talents are doing jigsaw puzzles and playing solitaire.
- On average, he gets three hours of sleep a night.
- His favorite foods are beer and sauerkraut.
- His favorite type of girl is "My wife".
- He is Polish
- His surname is also romanized as Noihus, as seen in Chapter 69.
- (To a Naberius) "You failed, huh... did you just growl?... No, you're laughing at me for falling low enough in the world to became a Demon's dog."
- (To Yukio Okumura) "You could say if you were chosen to act as the "brakes" of his power... I'm the "accelerator". It's all in order to take better control of Rin Okumura's ability."
- (To Rin Okumura) "I'll never forgive... Satan and all of those who go by the name of Demon!! Not to mention someone like the son of Satan!!!"
- Ao no Exorcist, Chapter 7, Page 44
- Ao no Exorcist, Chapter 69, Page 13
- Ao no Exorcist Manga: Chapter 2, Page 23
- Ao no Exorcist Manga: Chapter 5, Page 45
- Ao no Exorcist Manga: Chapter 7, Page 11
- Ao no Exorcist Manga: Chapter 7, Page 35