Aizen comments on the similarity of their Zanpakutō's agglutination with their arms as an evolutionary discovery, that perhaps that is the proper form they should take.
However, he says he understands the dimensions of their evolutions are different and that if he wished it, he could destroy Ichigo's in a single blow; he prepares a back-swing only for Ichigo to stop it barehanded as the earth around them shatters, pulverized by the sheer friction of the held strike. Aizen is stunned, his pupils dilating in sheer incomprehension; he could understand if Ichigo were to dodge it, even if Ichigo shouldn't be fast enough to do so, but for Ichigo to stop his strike is simply ridiculous to him.
Ichigo asks if Aizen is surprised because something he can't understand actually occurred. His voice, calm and deep, felt like a thunder in Aizen's ears.
Aizen pulls back, telling Ichigo not to speak so triumphantly, that he only managed to momentarily exceed his own physical strength and nothing more, something of a miracle.
Aizen decides to unleash a full incantation of Hadō #90 Kurohitsugi so as to prevent any further miracles by crushing him to atoms. The spiritual pressure of the Kido was a black, crushing weight, warping the light around it, a torrent of pure gravity.
Aizen lauds over his perfect casting with his power transcending Hollow and Shinigami to create a torrent of gravity capable of warping space-time in a way that a being like Ichigo cannot even begin to comprehend.
Ichigo allows the spell to surround him, the black energy completely engulfing him, only to shatter it with the simple, dismissive swing of his arm. The colossal black box broke like fragile glass, a silent, impossible defeat.
As it crumbles, he notes that Aizen didn't notice that he is stronger than him right now and that the mountain was obliterated not by Aizen's sword but by his. Ichigo rushes towards Aizen and wounds him, a clean, deep strike that drew a spray of golden blood.
Ichigo lands a strike across Aizen's torso, but Aizen instantly backs away in a flash of light from him to a nearby cliff.
Ichigo tells him that it's a strange feeling: when he put distance between them, Aizen asked him why, and now it is Aizen who is creating the distance.
Ichigo then asks Aizen the same question.
Aizen's wound begins to heal rapidly as he asks Ichigo if he liked that he had stopped his sword or if he is happy that he destroyed his Kidō and if he is happy he injured his body. His voice began to rise in pitch, a desperate edge creeping in.
He then becomes enraged and yells at Ichigo to abandon his human arrogance, his face contorted in a mask of wounded pride.
The diamond shape on Aizen's forehead opens up and develops into something similar to a horizontal third eye as Aizen transforms again, his very form a screaming violation of nature. He becomes what looks like a hybrid Arrancar creature with multiple wing-like appendages, which have Hollow skulls attached to the ends.
After which, Aizen states that he now sees the Hōgyoku will not truly allow him to lag behind a human.
One of the Hollow skulls fires a small spiritual energy blast, which has a devastating impact that can be felt all the way in Karakura Town and creates a large crater where it hit.
Ichigo survives the blast, but it destroys the upper half of his Shikakushō and singes his left arm he used to block the blast. The raw power of the attack had been successfully mitigated, but the pain was a searing shock.
Aizen says he sees that taking that attack only partially burned Ichigo, but that his left arm is most likely useless to him now.
He then moves to attack Ichigo, striking him and sending him flying into the newly created crater.
Aizen grabs Ichigo by the throat, the grip crushing, surrounds him with his Hollow mask appendages, and creates a circle of charged spiritual energy around Ichigo.
He asks Ichigo if he can hear him as he goes to theorize how at one point Ichigo destroyed the barrier between Shinigami and Hollow and became transcendental; yet, now Ichigo has lost the power he once possessed and has become a mere shadow of his former self. Aizen's tone was one of utter, supreme disappointment.
Furthermore, he says that in his current state, he isn't worthy of having Aizen absorb him and comprehend him; also, that Ichigo will meet death by a true transcendental being.
Aizen notes that being obliterated by him will completely free him from his inferior existence as both Shinigami and Hollow.
Ichigo looks up suddenly, his eyes burning with an incandescent light, and frees himself by slashing at Aizen's chest, thus forcing the latter to release him and likewise destroying the circle of charged spiritual energy.
Ichigo then tells him they should put a stop to this, as he is sick and tired of Aizen's logic. Ichigo readies himself and tells Aizen he wants to show him the Final Getsuga Tenshō.
Ichigo initiates the technique, causing Aizen to react in a flash of genuine, unadulterated surprise and alarm to the new form he has taken.
Ichigo transformed into a new form. He explains to Aizen that the Final Getsuga Tenshō means becoming the Getsuga itself.
He further details that if he uses this technique, then he loses all of his Shinigami power. That is the meaning of "final."
Aizen thinks to himself that he still can't sense Ichigo's Reiatsu and that he should be stronger than him because of how he has surpassed being a Shinigami and Hollow.
Aizen then comes to the realization that Ichigo is actually at a higher level than him, which infuriates him.
He screams at Ichigo that such a thing is impossible, as a mere human cannot surpass him. Ichigo calls for his Mugetsu, a wave of absolute, crushing darkness that swallowed all light.
...