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This article, Naiō Aizen, was added by November Blue who determines its usage on this wiki.

Naiō Aizen
Name Naiō Aizen
Kanji 靄然内奥
Romaji Aizen Naiou
Race Shinigami
Birthday February 26
Age Deceased
Gender Male
Height 5'10"
Weight 143 lbs.
Blood Type B-
Professional Status
Affiliation Himself
Previous Affiliation Seventh division
Occupation None
Previous Occupation Third seat
Team None
Previous Team Seventh division
Partner Wanqihun
Previous Partner None
Base of Operations Yāolù
Personal Status
Marital Status Widower
Relatives Sōsuke Aizen (son)
Education Shinō Academy
Status Active
Shikai Kazeatari
Bankai Not revealed
"The double-edged sword of society."

Naiō Aizen (靄然内奥, Aizen Naiō) is a powerful and manipulative shinigami born many centuries before most of the current captains of the Gotei 13. He is also the father of Sōsuke Aizen, the man who carried on Naiō's work after his death at the hands of his dangerous offspring while in Yāolù. Despite being murdered by Aizen, Naiō found a man who agreed to allow Naiō to inhabit his body, thereby continuing to live. Since his death, he was obsessed with ruining his son's plans, although a human named Ichigo Kurosaki beat him to the punch. After discovering that a mere human had beat Aizen, Naiō has sworn to destroy Soul Society for entrusting their survival with a weakling such as a human.


Before his death at the hands of Aizen, Naiō had a strikingly similar appearance to his son. However, he lacked the glasses that Aizen wore during his time in the Gotei 13. Attire-wise, Naiō typically wore the standard outfit for any seated member of his division: a shihakushō, white obi and traditional sandals. As for his facial expressions, Naiō was constantly seen smiling, even if the situation was anything but happy. His eyes are also constantly in slits, hiding the colour of his eye, which is known to be the same shade of brown as his son. His hair is also very scholarly in appearance, being very shaggy for someone in the thirteen military divisions.


Much like his son, Naiō was an extremely intelligent and manipulative man, even when he was a child. He believes everything to be a giant chess game, with him as the king and the rest of the world his pawns. He cared little for anyone other than himself, going as far as to stating that he'd kill his own flesh and blood should he prove to be worthless. Unlike Aizen, Naiō did not attempt to hide his true nature, finding that to be "too much of a hassle [for me]." Besides Gin Ichimaru, Naiō was the only person in all the spiritual planes that was capable of seeing through his son's manipulative nature. However, his selfish ambitions blinded him to Aizen's plans to murder his father, which would be his downfall.

After his death and fusing his soul to Wanqihun, Naiō began to exhibit traits borrowed from his partner, although he still kept his incredibly manipulative nature, which he had shown to benefit the man. Naiō's traits from before his murder were quite present in the sǐwáng, telling his partner that these traits would help the man further his own goals, although this was blatant lying on Naiō's part. While residing in the man's soul, Naiō has come to utterly despise his son, wanting nothing more than to just kill him, even though they shared ideals on the world. During a mental conversation with his partner, Naiō stated that it was sad that he'd have to "kill off such a worthy adversary," and going further to say that his son was, possibly, the only person that could match his intelligence.

During battle, Naiō was still incredibly similar to Aizen, wanting to draw out a conversation for as long as possible, much to the dismay of his opponent's. Despite his attempts to make small talk, Naiō often had entire situations planned out well in advance, making any sort of victory close to zero for his adversaries. Because of this advanced planning, Naiō was very cautious in battle, wanting everything to go as he had planned. When something failed to stick to his plan, he'd quickly begin to become reckless and attempt to bring everything back into the way he planned. This was what made Naiō stand apart from his child in combat, as Aizen was very casual and uncaring, keeping calm even if a situation he had not expected to arise had been presented before him.


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Part II[]

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Powers and abilities[]

Overwhelming Spiritual Energy: Although his son was equally manipulative, Naiō surpassed his son in spiritual energy, as well as in other abilities. While Aizen had twice the amount of a normal captain of the Gotei 13, Naiō possessed a startling amount of three times more than the average captain did. After his fusing of his soul to Wanqihun, Naiō's reiryoku skyrocketed to new heights. His spiritual energy was theorized to only be surpassed by Hao Baojia, the captain-commander of Yāolù's military, who possessed the highest known amount of reiatsu in all of Yāolù. Because of how enormous Naiō's reserves are, he must lower it a substantial amount to allow others to sense it, which only serves to boost the shinigami's already colossal ego.

Immense Speed: Considered the fastest shinigami alive before the goddess of flash was born, Naiō is overwhelmingly fast. This speed is unsurpassed by all but Yoruichi herself, who can only keep up with Naiō, not surpass him. Because of this tremendous speed, Naiō does not need the assistance of shunpō or any other form of speed enhancement.

Expert Swordsmanship Skills: Due to his zanpakutō's ability, Naiō rarely utilized any other form of combat, relying solely on his shikai's ability to defeat an opponent. Despite that, he has been shown to use his skill in zanjutsu to defeat weaker opponents who he deems "unworthy of seeing my blade's true power." He has shown himself to be a practitioner of kendō, gripping his blade with two hands and slashing at his opponent's with incredible force. While utilizing kendō, Naiō has been seen being able to defeat opponent's in very few strikes, if more than one is even needed.

Genius Intellect: Naiō's greatest ability - even more so than his zanpakutō - is by far his intellect. Similarly to Aizen, knows much more than the average shinigami should, and would know about, most notably his knowledge of the dimension of which the Soul King resides in. This knowledge, as well as his desire of the ōken, is what would shape his son's ultimate goal of being the Soul King many years later. Besides his amount of knowledge, Naiō can easily deduce the abilities of any given opponent, no matter how complex they are, making defeat utterly impossible for all but the strongest of the strong. However, this level of intellect was a double-edged sword, as it brought Naiō to his demise by the hands of his son.

Expert Hand-to-Hand Combatant: Much like his skill in zanjutsu, Naiō rarely has to rely on his hand-to-hand prowess. However, he has no problem disposing of opponent's should the need for hakuda present itself, albeit very seldom. He has shown himself to be proficient enough in the art of close-quarters combat to defeat multiple foes without breaking much of a sweat, although he is quite tired after doing so. Despite it not being his best field of combat, Naiō has no problem dispatching an adversary with hakuda, however rare that may be.

Immense Strength: Naiō, despite being quite frail in appearance, is very powerful. He has been shown to send opponent's flying with a simple flick, as well as shattering boulders with the same gesture. Because of this strength, Naiō quickly tires, which is possibly why he didn't use it as frequently as he should have during his lifespan. However, this is mere speculation, as perhaps Naiō just simply felt no one was worthy of his might.

Kidō Master: Much like his son, Naiō is a dangerous combatant if the use of kidō is necessary. Typically the first type of combat Naiō will resort to should he not use his zanpakutō's ability, kidō is like a sixth sense to him. His favorite spell, in particular, is Hadō #90 - Kurohitsugi, a trait which he passed down onto Aizen. This spell, being his favorite, he has learned to use it without incantation to it's full effect, as well as experiment with it to use it almost any plausible way. Besides Kurohitsugi, Naiō is particularly fond of three other spells: Bakudō #79 - Kuyō Shibari, Hadō #54 - Haien and Hadō #88 - Hiryugekizokushintenraiho, but this fondness pales in comparison to his love of the Kurohitsugi spell.

Master of Manipulation: Coming in as a close second to his intelligence, Naiō's manipulation abilities are surpassed by no one, not even his son. He is quite crafty and cunning, being able to manipulate and bend others to his will as if they were putty. Through this manipulation, Naiō would deceive any and all of the people he encountered. Because of his dependence on his beguiling abilities, Naiō has begun to think of life as a never-ending chess game, with him moving his pawns around on the chessboard and making sure they fulfill the role he had assigned them, something he did flawlessly up until his death. Before his death, Naiō was obsessed with finding the illustrious ōken, an obsession that caused his murder.


Offense Defense Speed Reiatsu Intelligence Stamina Total
85 90 95 100 100 65 535


Naiō's zanpakutō, named Kazeatari (風当たり, Japanese for "being subject to outside pressures"), takes the form of a regular katana with a sky-blue handle. The tsuba is in the shape of a star with four points, with it's colour being a distinct goldenrod.

  • Shikai: To release his shikai, Naiō must speak the release command, which is "subject" (種, "tane" in Japanese). However, nothing changes on the blade, making the release go unnoticed if Naiō mumbled the release command under his breath.
Shikai Special Ability: Much like his son's Kyōka Suigetsu, Naiō's Kazeatari's ability revolves around controlling the opponent's five senses (sight, hearing, touch, taste and smell), although their is a significant difference in how their abilities work. Instead of having to see Kazeatari's release, the opponent will not fall under it's effects unless they show distress, such as anger, sadness and/or doubt. By feeling a fluctuation in an opponent's spiritual energy, Kazeatari will take advantage of it's opponent's moment of weakness and cause them to fall under it's spell. After being cast into Kazeatari's ability, an opponent is under complete hypnosis, subjecting the opponent to Naiō's will, per say. The only way to be relieved of the hypnosis is for Naiō to turn it off by force of will, making any and all attempts to fall out of it's influence hopeless. However, unlike Kyōka Suigetsu, Kazeatari's ability isn't long-lasting. Because of this, each time an opponent faces Kazeatari, they must show distress during battle, making it perhaps a weaker variation of Naiō's son's zanpakutō.

Behind the scenes[]

The idea for Naiō came after re-reading the "Deicide" chapters of the manga, where I realized that Aizen's heritage had never been explained. After that thought, the majority of Naiō's character came flooding into my brain, which I immediately posted, seeing as the thoughts would be much more prominent if fresh in my mind.


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