Honestly, flies, and at this time of year? The buzzing sure is annoying

Ive read the posts and i think its a complete misunderstanding. Crazieone seems to be saying his opinion in a sort of future tense; a maybe, whereas yours is in past tense; a firm resolve, which makes it seem that you want to enforce your belief that a character doesnt have a specific ability. Which of course annoys him greatly.

And a troll has no grounded resolve; Crazieone is just another intellectual.

I put the forum up so we acould actually discuss it wothout getting into a war over it, something I'm not entirely certain Crazieone is capable of doing. I have no doubt that he is intelligent, but he lacks the capability of having a debate without insulting people, getting angry and then making out to be some big joke.

My whole point that I was trying to make was:

- I think Aizen used Shikai during his Captains Exam, so that the examiners thought they were seeing a Bankai.

- I think Aizen was smart enough to plan some of what he was doing with the Hogyoku (there is no doubt in my mind that, even if he didn't know how powerful he was going to get, he still wanted to outclass Shinigami and Hollows.

- I think Aizen planned some of that because he is highly capable of planning things like that. He had begun his plans with the Hogyoku around the time he tried to hurt Rangiku and Gin swore to kill him one day.

Crazieone doesn't understand how possible this is... Maybe he has a Bankai and maybe he doesn't, but, either way, I think he doesn't and this is because I think he didn't like Shinigami powers and he only used his Zanpakuto because it helped his plan. You'll notice that he stopped using Kyoka Suigetsu's ability once he transcended.

Btw, maybe Crazieone isn't a troll, but, if that's the case, he should stop acting like one. Maybe it didn't start off that way, but calling someone inferior to yourself is just plain rude and something I'd expect a troll to say...

Does anyone else want to add an opinion? Honestly, I am quite happy to hear someone's point of view. I won't be rigid and insist only the fact that Aizen has a Bankai, or not. It would refreshing to have a different angle on the subject at hand...

i think he did have a bankai........but he was solely relying on his shikai and hogyaku to reach an ultimate level beyond soul reapers and espadas.............if incase he wanted to use the bankai that means his shikai was a failure.he also intentionally didnt show kyoka seigetsu to ichigo eventhough he is strong....his shikai was too powerfull to begin with............and his purpose was to merge with hogyaku and destroy karakura town and make the ouken..........

its like a 50\50 now that BP has pointed out that it could be part of the his shikai that may have made it look like he did have a bankai. Maybe he did have bankai but tite is saving it up for later but if he does have one than why didnt he use it in the battle aganist ichigo?

@Unohana. I don't recall saying it was a part of his Shikai, I remember saying that if Aizen didn't have a Bankai, then he would have used his Shikai's abilities to put the people, in the Captain Proficiency Test, under his Complete Hypnosis and then tweak his Zanpakutou's appearance so that it appeared that he had released something with the flashiness of Bankai (bearing in mind that Aizen would have already been incredibly powerful, even at that point).
If he had a Bankai, why didn't he use it in the battle against Ichigo? At first, he didn't need anything to beat Ichigo, even Gin managed to give Ichigo trouble... It wouldn't have been any use at that point. After Ichigo came out the Dangai, Aizen had already transformed several times from the power of the Hogyoku... As his goal was to achieve a power beyond that of Shinigami and Hollows, he had no need to release a Bankai, as he had already achieved one of his wishes... Even so, the transformations from his Hogyoku metamorphosis were incredibly powerful and I doubt his Bankai (if he has/had one) would have been anywhere near powerful enough to defeat Ichigo, or it's ability would have been useless against someone with such a power.

alright, understood

Maybe hes hates his bankai

i say he have a bankai...........but his shikai itself was too powerful for others.............so didnt care using his bankai............and most probably he was solely relying on hogyoku............to transform into a ultimate being..................only ichigo didnt see his shikai release...........bcz he need a challenge with his new born power..........if his shikai is that powerful i cant imagine what and how powerful his bankai is...............its making my sking quiver................that makes him the powerful soulreaper in soul society even in squad 0..................

ichigo lost his power while fighting aizen..............whole society was down if it isnt kisuke who didnt stop him with that special kind of seal............he migt be the new soul king now.....................

I'm not sure if Aizen has a Bankai or not. I'm pretty sure that when he went to take his Captain's Exam (which I'm sure the Head Captain was allowing a lot of people to do since there was a massive drop in captains.) that he didn't use a Bankai. He used his Shikai and it's abilities to make an appearance. He then used a mist to hide his appearance (in case he wanted to create a visual illusion) and they can feel the power (or what he wanted them to feel). But if he manipulates all 5 senses, then how can they not "sense" that his power isn't as strong as it really is... He can manipulate sight, touch, smell, sounds, and taste. But that doesn't change your ability to sense things. Maybe, you don't "sense" power but feel it. If that is true, then he clearly used his Shikai ability during the Exam and made it appear to be something it's not. All he had to do was create a little lie, or "stretch the truth" like Gin. So I'm not sure he ever achieved his Bankai, but I'm pretty sure he didn't have one or use it during the Captain's Exam.

So my thought. He might not have one. PLUS before he became a captain he was already working on the Hogyoku and his plan. So he had an idea of what he was doing, but didn't know exactly HOW powerful he would become. All he knew is his power would easily surpass any Hollow or Shinigami. He knew he would have to transform, but only WAY later did he learn that. Before that all he knew is it could grant wishes, and he sure had a big wish. But other than that, I don't think Aizen ever achieved it. He might have tried, but I don't think he put as much effort into it as the people who DID achieve Bankai because his attention was focused on bigger things.

I have been reading all of your post and would like to add something.

Now, if I rember correctly Aizen did not use his zanpakotu ageist Ichgo. That ways when he had transformed into something that can only be called a monster.

Now his zanpakotu controls the five senses. Which means his bankai if he has/had one would have similar powers to his shiki, but here's the punch line, what would the powers of his bankai be? If not simply strengthen his control over the five senses.

If he did have a bankai and it had the same powers has his shiki, then it is possible he was using his bankai the intoner time.

Basically think of it this way. Lower the power of his shiki so it only controls one of the five senses at a time, let say touch for now. Now when he uses his bankai, witch we all think is his shiki then he can control all five at the same time.

So the way I see it is, it is possible that he has been using his bankai the whole time, while everyone else thought it was a weaker shiki.

Also with this in mind. I could also mean that Aizen did indeed use his bankai at the captain exam. Now he may have not shown it's true form to them, but he could have used his bankai to fool them.

Now remember this is just a possibility and can be denied. For we all know that zanpakotu change shape when called into their different forms. But there are rare ones that never seem to change at all for example Sen Bon sacora. This zanpakotu takes the form of cherry blossoms and when called into bankai it does not change shape but simply adds more blossoms. So I find it highly possible that he has been passing off his bankai as a shiki. And we have see that soul reappers and hollow's alike think that a weapon in shiki form is not a very big deal. So he could have used this to his advantage. Because everyone thought it was a shiki they let their guard down and made it easier for Aizen to use his powers on them. When you think of it this way he has/was using his power to fool people to his full advantage. Soul reapers even if they are focus and ready to fight Aizen, they would still underestimate his weapon by simply thinking that it's a shiki when really it's a bankai.

I honestly don't think he did achieve bankai, there were situations where he would have used it if he could. Think about his inability to directly fight yamamoto. A lot of unnecessary circuity to his plan could have been avoided if he could flat out step up his game. Yes he was insanely strong but that is not what a bankai is. It's a deeper relationship between the soul of your blade and yourself. Power is not the main factor. Look at kenpachi, inarguably one of the strongest characters in the series, yet he hasn't even achieved shikkai. It's all relative.

Honestly, I can't fathom when people argue that Aizen did not achieve Bankai. It isn’t a matter of not possessing a Bankai, rather never having a reason to use it. Aizen's strategy from the very beginning was to neutralize his enemies without needing to assert his own strength. He assembled the Espada for the distinct purpose of defeating the Gotei 13. It was not until they were all defeated that he was forced to draw his own blade. His logic was clear the moment he revealed Wonderweiss, having modified him for the sole purpose of defusing Yamamoto’s zanpakuto. While he may have been concerned about his capacity to defeat Yamamoto head-on, his strategy was eliminate his involvement altogether. Quarreling with the captains, especially Yamamoto, would have been time-consuming and potentially fruitless. His method was much more logistical, having created a method for eliminating Yamamoto as a primary threat. This serves as another testament to his strategic genius, not having to charge in head-on to defeat enemies. He saw the benefit of eliminating threats from a distance. The argument that he does not have it because he has not used it is not entirely sound. If that logic were applicable, then that would mean that Shunsui and Ukitake do not possess Bankai, otherwise they would have recognized the gravity of their situation and released like Soi Fon, Toshiro, and Komamura. Again, I don’t think what transpired was evidence of him not having it, rather his clear display of genius, having created so many methods for subduing the Gotei 13 and not really having to do much himself aside from observe patiently.

You make a fair point craz....and i can both see and understand your reasoning. So I will just say that if Aizen does have a bankai then he truly never used his full power. Yet in his battle ageist old man Yama he should have used his full power to make sure that Yama would die. However when i thing about it because he is used to fighting at a distance then it's a no-brainer why he never used his full power.

Maybe, just maybe (even though its probably not true) he didn't learn his Bankai because he needed extra power to for his Shikai, maybe he couldn't perfect his technique if he had a Bankai. I only had this idea cause of what Captain Soi Fong said in the latest arc. I know it's not right but it's a theory just the same.

The only reason this argument is going on is because he didn't use his Bankai against Ichigo when he knew he needed more power to defeat him but saying that he didn't use his Shikai either.

Aurora....I can exsplain why Aizen didn't use his zanpakotu when he fought Ichigo...becouse he couldn't. From what I understnd Aizen lost his soul after takeing on his final form and in turn lost his zanpakotu. Now this is how I see it, if anyone else has another opinion plz share it. And I still say that Aizen could have been useing his Bankai all the time, makeing everyone else think it's a shiki. One more thing if he did have a bankai...what would it's powers be?

Yes, there was the implication that his connection with his Zanpakuto was destroyed, though he confused the swords disintegration as another form of evolution. However, you must consider another reason why he didn't utilize his zanpakuto during his battle with Ichigo. His reasoning, before his official defeat, was simply because he had transcended beyond his zanpakuto's abilities, obtaining power far greater. 'Why utilize an inferior technique', was likely his logic. Moreover, he traversed the line separating shinigami and hollows, becoming an amalgam of each, and something noticeably stronger. So, again, his actions were not a sign of a deficit on his behalf, but a recognition of what was transpiring in the moment.

Yet when you think about it losing his zanpakotu seemed like he lost his soul reaper powers (other than kido) And then after his sword was gone for good he just seemed to turn into a more powerful hallow. See...if you think for a moment the one think all soul reapers have that shows they are soul reapers is their zanpakotu. But Aizen got cocky and saw the lost of his as a from of evolution when really he just turned into a more deadly hallow with no soul reaper powers. If he surely become something stronger then both hallow and soul reaper then why doesn't have the most powerful weapon on a soul reaper? Instead he just uses his hallow power...indicating that he is just another hallow. A more powerful one yes..but just a hallow. In fact the Arrancars are closer to a high bread of hallow and soul reaper then Aizen was. But this is just my opinion.

This argument seems a bit circuitous. However, It would take me a while to adequately explain the flaws in your argument, namely that a Soul Reaper is defined by their Zanpakuto. Posession of a powerful Reiryoku, and subsequent mastery, place someone on a trajectory to become a Soul Reaper. To be fair, Soul Reaper is both a status and role, not a species. What separates Soul Reapers from Hollows is their humanity, of sorts. It gets rather blurred because we are to assume they are "deceased" humans, or "transformed" pluses of some kind. And, as we know, Humans are the opposite of Hollows. If anything, a loss of one's Zanpakuto represents a hindrance to their performance, more so than to their identity as a Soul Reaper. A Zanpakuto is merely one of many skills sets accessible to someone of that caliber. If he possessed Kido, he was still a Soul Reaper.
And while I understand where you're going with this, I do not believe it captured the way you're framing it. Use of a Zanpakuto was of trivial concern to Aizen. The thing that separated him from the others was his magnitude of power, boasting something greater than those utilizing their Zanpakuto. His goal was to transcend beyond both entities (Soul Reapers and Hollows, respectively), which he did. Well, he transcended beyond the Gotei 13, but Ichigo is some enigma who possessed powers beyond even Aizen. If you consider it, I believe this is an issue with the manner in which the story was developed, more so than our arguments. There are a lot of inconsistencies, of which I have no idea how to explain.

I see. Well then the argument of Aizen and Ichigo is just like a comparison of a hallow and soul reaper. Aizen joined hallows and became some sort of high powered super hallow. But with Ichigo...he fussed with his zanpakotu. So when you think about it Aizen should have focus more on his zanpakotu and increase his powers that way...then once he became something similar to Ichigo's new form he could have worked out how to improve his hallow powers. When I think of it this way Aizen chose second best when he could have been number one.

Again, your logic is becoming increasingly circuitous. Aizen had no control over how the Hogyoku amplified his power. The Hogyoku was free-thinking, and therefore, did as it pleased. The augmentations were spontaneous, generally incited by some common threat. If he had any manipulation over how the Hogyoku imbued him with strength, I doubt he would have continuously analyzed these transformations. He even said, something to the effect of, "You do not want me to be defeated by a human." He indicates that this was the Hogyoku's will, not his. It isn't an issue of who was a hollow, soul reaper, or not. Aizen was distinctively a Soul Reaper, whereas Ichigo had active agents diversifying his abilities. The only thing that enabled Aizen's change in powers and appearance was the Hogyoku, not some innate characteristic. Moreover, Aizen's power was far beyond his Zanpakuto. He believed he had transcended so far beyond Shinigami and Soul Reaper, which he had, that a Zanpakuto was of no concern. I'm not sure why you're even arguing that Aizen should have done this, as opposed to that. It doesn't really align with your earlier logic and is rather tangential.

Alright you got me there, but I would like to ask if Aizen did have a bankai and never used it, what would be the powers of his bankai? His shiki controlled the five scenes of the human body so what would his Bankai be?

And that's what I thought then I got to think. What if Aizen has been using his bankai the whole time? If you think about it is sword is over powered for a shiki. But if he was using his bankai the whole time the his zanpakotu's power fits.

I'm glad people are still utilising this forum... I had thought it was pretty much done with, until a few months ago, when people began to debate the topic again.

I have to also wonder what the Bankai could be, despite the fact that it would be rather difficult to expand the power of the senses beyond what Aizen already could use with his Shikai... perhaps it would have been something to increase his control over the senses... we know that he could essentially manipulate the five senses, causing his opponent to lose control of their own senses, but I can't say for certain whether it would be possible for the control over the senses to increase at all. Maybe his Bankai would give him the power to manipulate a sixth sense, which I presume would logically have to be spiritual sense... I have no idea how that would work, though.

Did Aizen's Zanpakuto fade away, from being destroyed, or was it because the Hogyoku determined that he had no need for it?

thats an amazing question. i know a person who knows tons on bleach. i'll ask him and get back as soon as possible

"yes. obviously because he's a captain" he said

It seems like the latter answer was insinuated. The reason appeared to be that his blade was deemed unnecessary by the Hogyoku, though for the life of me I can't figure out why.

It would be interesting, though, if his zanpakuto was somehow still in effect, and that he'd essentially sent an illusion of himself down into the bowels of Soul Society. I think there would be an awful lot of questions there as to why, but I could think of one or two plausible explanations. Wouldn't it be crazy if he's been masquerading as Ishida, for example? Oh man, and with recent events in the manga... wow, that would be an insane explanation but fantastic.

I'm surprised no one offered a 'non-answer' yet. I guess I'll be that guy.

It's not really a matter of 'did he have it or not'. Being able to attain bankai is entirely a plot point. 'Not everyone can do it'. This one fact indicates that it's a potential you're born with, so you don't know if you can attain it or not until you try. Supposedly. Remember; that was closer to the beginning of the series. Now we're at the point where the vast majority of soul reapers who's faces and names we remember have a bankai, regardless of whether they're a captain or not.

Just to point out a few o points you all made that are kind of backwards; Aizen did, indeed, falsify his zanpakutou in front of everyone so that they wouldn't know it's real ability. He basically used his shikai to make everyone think that his shikai and bankai were something else. Did he actually use bankai? Probably not. Does that mean he doesn't have one? Nope. He faked it, but it doesn't mean he doesn't have one. On the other hand, is it possible for someone of such great strength and ability to NOT have a bankai while able to cut down other captains using their own bankai using only his shikai? Of course it's possible. Kenpachi didn't even have a shikai, let alone a bankai. Maybe, for all his strength and power, Aizen wasn't able to use bankai. We don't know if he had the trait, since we don't know the criteria. That wouldn't stop him from being strong and having an overpowered shikai.

Think about it from the author's perspective. Overpowered villain who can take anyone down single-handedly, possessing a shikai that can falsify anything by controlling the five senses. There are some problems here. The only way you can improve that with a bankai is to let him alter reality freely (I could explain the problems, but I think you can imagine why it's easier to just NOT do that). Notice, throughout the entire Arrancar Arc, not a SINGLE PERSON mentioned Aizen's bankai at all. They went into battle, prepared with countermeasures for only his shikai (horribly shoddy countermeasures that hinged on the main character, but meh) and didn't even stop to consider what his bankai could be. Then the Hogyouku event happened and he lost his shikai in exchange for even more power. So he never tried to use his shikai on Ichigo and he cast aside his overpowered zanpakutou for physical strength? That shoddy plot development is all the author's fault. He just didn't want to both with Aizen's bankai, so he got rid of it. You can just see how he skirted around the issue. I mean, with just his Shikai, Aizen could have feasibly defeated Ichigo's Mugetsu. Just let him fight a fake until he loses his powers then kill him afterword-- that easy.

(Plus, if Aizen's shikai could affect touch, then it leaves me to wonder just how he couldn't have just materialized imaginary spikes in everyone and killed them off. Kind of a grey area as to what he could have managed there...just saying...)

Long story short, it's not a matter of 'did he or didn't he'. All the information in Bleach isn't enough because we don't know the key facts: 1) What is the criteria for being able to attain bankai? 2) Did Aizen meet that criteria? Unless the author makes it so, it can be whatever he wants using any explanation that he feels fits. Cause clearly he's been doing whatever the hell he wants in the most recent arc...

The real issue is his unexplainable strength. Why was he such a superior being to begin with? If his loneliness is what spurred him to do all that he did, where did the strength that set him apart from the others come from? Three explanations come to mind with what information we do (and don't) have. Aizen could be using his bankai, which is what we know his shikai to be (which would help explain his strength a little). Perhaps his bankai is the same as his shikai, just with different range or potency (much like Toshiro's bankai and Shikai have a negligible power difference, but the bankai has a greater quantity of ice).

The last explanation is purely my hopeful speculation to fill in the gaps: The powerful Aizen wasn't a soul reaper to begin with, but was a first class singularity who looked liked a Soul Reaper and blended in unconsciously with his ability to control the five senses (or distort reality). Vaguely aware that he was different from those around him, he was drawn to other anomalies, which attracted him to the arrancar and visoreds. He never had a zanpakutou to begin with--which is why the Hogyoku got rid of it--and the form he was given is his true appearance. So rather than not having a bankai, it's more of a matter of him already having all the power he could obtain, but wasn't aware of it. A being that's different from soul reapers, perhaps something original, a parallel to the Soul King himself, maybe even a seperate special of soul reaper...

Damn it, Kubo, don't screw this up!!!

While I can appreciate your fairly logical position on the matter, I don't believe it is related to or dependent upon "meeting criteria." Like any stage in development, Bankai both grants great power, but requires significant power, too. It would be much too scientific to argue that there are a universal set of criteria, not unlike a set of nomenclature you'd use to classify an etiology, to indicate someone's worthiness for obtaining Bankai. It is likely a product of someone's willingness to seek and foster a relationship with their Zanpakuto and endeavor to overcome obstacles that are unique to themselves, for example, self-doubt or other personal handicaps. Ideally, everyone would be able to obtain Bankai, if they are sufficiently capable of obtaining Shikai. There is a uniqueness to the process, most likely similar to any other developmental process. Not everyone obtains Bankai at similar times and their strength upon achieving Bankai might vary. The differences among each person likely weigh greatly in their ability to both achieve and control their Bankai.

It is far too ideal, and rather preposterous, to consider Aizen as anything other than a soul-reaper who just happens to deviate greatly in strength. Just like any other race, there are different levels by which people express their abilities. Some are far more adept due to training while others have natural skill that appears effortless in nature.

If we insist on looking at it from the story's perspective, we can at least agree that achieving bankai necessitates growing closer to one's zanpakutou, right? As we've seen numerous times (with Ichigo attaining bankai, Yumichika supressing his shikai by intentionally using the wrong name, Zabimaru never telling Renji its real bankai name, the zanpakutou's smith's lecture toward Ichigo, so on and so forth), that's at least a requirement for gaining a bankai. Can you really say that Aizen, who renounced being a soul reaper, claimed to be something more and was entirely obsessed with becoming more, would really take the time to bond and grow with his zanpakutou, which he clearly viewed and abused as a tool? I'll admit that he might have been willing to go that far for the singular purpose of getting more power, but then I'd be more confused as to why he didn't use it and why he would have been so 'lonely' while searching for an equal.

That latter part was meant to be preposterous; it's a dramatic plot twist that I came up with based on the information that we do have. It's just the scenario I would find interesting, and it's exactly the direction I would go in if I were Kubo. See, the 'just happens to deviate greatly in strength' is the problem I have. We can't say that he's a 'talented soul reaper who went down the wrong path', because that niche is taken up by both Kenpachi and Gin--as well as Toshiro, by extension. Aizen boasted natural strength that surpassed the natural limits a soul reaper his age should have, proving to be a threat to even Yamamoto. That's why I felt that the only viable way to explain the fact that he's just as much as a singularity as Ichigo--the main character--is that he, too, is not simply 'just a soul reaper'.

To a relative degree, yes, which is how all Captains have achieved it. Obviously, there is something they have that other Shinigami don't. Ichigo obtained Bankai, though he had a relatively average relationship with his Zanpakuto at the time and the relationship wasn't anything special compared to any other Shinigami... then we learned that it was only a poor image of Ichigo's Bankai (something I have heard about, but, since I don't read the manga, I don't know the full story of). No, we can't say that, because that's not what happened... he definitely had enough of a bond to at least obtain Shikai... also, nothing was ever shown between him and his Zanpakuto - we know that he treated it like a tool, to a certain degree, but he never said anything else of it and nothing else was really shown. What you're saying seems to support that he didn't have one i.e Can you really say that Aizen, who renounced being a soul reaper, claimed to be something more and was entirely obsessed with becoming more, would really take the time to bond and grow with his zanpakutou, which he clearly viewed and abused as a tool? I'll admit that he might have been willing to go that far for the singular purpose of getting more power, but then I'd be more confused as to why he didn't use it and why he would have been so 'lonely' while searching for an equal. That, to me, implies that you think he wouldn't have bonded with his Zanpakuto and, potentially not gained the power of Bankai, or that 'singular purpose of gaining power', which I assume you are referring to Bankai. Either way, we don't know, but everything that has been said on here helps to think a little more about the subject.

The relationship that exists between a Zanpakuto and its master is not dependent upon whether he or she identifies as a soul reaper. We know from the story that Zanpakuto often reflect their master's ambitions and ideals, often going to great lengths to help them in their endeavor. As one half of the whole, it is reasonable to assume that his Zanpakuto was very much in agreement with his objective. It wasn't until Aizen believed he evolved beyond a Zanpakuto, in the final moments of his life, did he necessarily embody the notion that he was unneeding of his blade. One could easily presume that his Zanpakuto was quite involved in the same logic, believing it too would grow with Aizen, not simply Aizen as a separate part.

As for Aizen's loneliness, I can't really speak to that. This was, of course, acquired from an interview where Tite Kubo attempted to articulate why Aizen behaved the way he did. Purely from a psychological perspective, though this is a fictional character of whom operated as he was written, so he had nothing more than script to guide him, loneliness is not always perceived by the self the same way it is by one's environment. Complex feelings of isolation, loneliness, feeling misunderstood and anomalous can manifest in a myriad of ways, spawning feelings of resentment, superiority, and revenge seeking. I'm not going to evaluate the complexities of Aizen's psyche because he is, in fact, a character that Tite Kubo manipulated and was not a product of a genuine psychological process. I believe it is possible that Aizen felt compelled to transcend above all overs and herald in a new world whereby he was at the helm. It made sense to him because he was, in many ways, superior, and felt deserving of the title.

Hello, I am also a fan of bleach and thought I would put my two cents in even though the thread might be dead. I am a believer that Aizen did not have a bankai and here's why. In all cases of people who had bankai's the people could communicate with their zanpakuto. They must first figure out the name of their zanpakuto and then form and grow a relationship with them. I believe Aizen started that relationship but never continued it. It was at the end of his battle with Ichigo, episode 310, that Ichigo said that all he felt from Aizen's zanpakuto was loneliness. From that I assume that it meant that he was no longer communicating with his zanpakuto and that he never built a relationship strong enough to reach a bankai. It could also mean that he gave it up after he had learned bankai but my gut is leaning more towards the former than the latter. A bankai is a manifestation of your zanpakuto which is a part of yourself. The fact that when he thought him and his zanpakuto were becoming one at the end of the battle and he was "evolving" just proves to me that he hadn't built that relationship with his zanpukuto. If he had built the relationship and achieved bankai then he would have turned into something similar to Ichigo's final form.

That wasn't the case. Instead, he had been relying on the hogyoku's power instead of his zanpakuto making it seem that he never really believed that his zanpakuto was a part of him. In the end, Aizen was just being manipulated by the hogyoku. It wanted a master so that it could grant it's master's wish. When the hogyoku thought that Aizen's power was not enough it gave him a boost because even Aizen wasn't aware that he was going to evolve further. It kept doing this until it realized that Aizen was not fit enough to posses it anymore and gave up on him. If it's purpose was to grant its masters wishes then it would not have abandoned him showing that the hogyoku was actually following its own agenda and not Aizen's. In the end Aizen wasn't the bad guy the hogyoku was. Anyway that's my input.