Arrival in Karakura Town

 was the beginning of Sōsuke Aizen's invasion of Soul Society. This begins his quest to the creation of the Oken.

Prelude
After stopping Gin Ichimaru from attacking Ichigo Kurosaki any further, Aizen instructs his accomplice to open a Senkaimon, as it would better fit his plans to attack the real Karakura Town in Soul Society. Isshin Kurosaki quickly recovers from his fight against Aizen, and urges Ichigo to open another Senkaimon and follow Aizen and Gin.

As Aizen and Gin they travel through the Dangai, Gin comments on the nostalgic feel of the place. Aizen agrees before they are confronted with the. Gin urges Aizen to get going, but Aizen holds his ground, prompting Gin to comment that as the Kōtotsu is a being of reason and not Reiryoku, nothing can be done to it with Reiatsu. However, Aizen continues to hold his ground and then destroys the Kōtotsu as it gets close. Aizen then asks Gin what he is afraid of, saying that reason is for those who cannot live without clinging to it. Aizen then invites Gin to come with him towards reason's horizon.

Seeing as Ichigo continues to stand in awe, Isshin head butts Ichigo to get his attention, asking him if he heard what he said. Ichigo plainly states that it is hopeless. Isshin yells to him that he doesn't know if it is hopeless or not. Ichigo replies that they both know they cannot beat a monster with Reiatsu like Aizen's. Isshin then realizes that, unlike himself, Ichigo is able to sense Aizen's Reiatsu. He tells his son to come with him. When Ichigo lingers, Isshin asks what Ichigo intends to do instead. He yells at Ichigo, asking if he is just going to stand there crying about how he couldn't protect anything. He asks Ichigo to think carefully about the meaning of Aizen going to Karakura Town; he reminds Ichigo that if he does not go, everyone within Karakura Town will die by Aizen's hands. Ichigo's resolve returns and he asks his father to open the Senkaimon.

Arrival
Once they arrive in Soul Society, Aizen notes that they are some distance away from their target. Gin asks Aizen not to make it sound as if it was his fault, blaming it squarely on Aizen's behavior in the Dangai. Aizen concedes that that might be the case and apologizes. He and Gin walk towards the Human World town. As they run through the Dangai, Isshin orders Ichigo to stop. Ichigo asks why they are stopping while in such a hurry. Isshin explains that he can't sense the Kōtotsu and says Aizen must have done something to it. Ichigo asks if it will be a problem and Isshin replies that it can be if left that way, but for the time being they can use it for their advantage. Since the precipice world is cut off from time and space, making it the perfect place for Isshin to pass his teachings. When Ichigo asks him what he wants to teach him, Isshin replies that he plans on teaching him about the Final Getsuga Tenshō. As Aizen and Gin make their final steps towards Karakura Town, Keigo Asano is waking up from his sleep.

Training: The Final Getsuga Tenshō
Ichigo asks why his father wants him to learn in the Dangai. Isshin explains that due to the structure of the Dangai, time is 2000 times more compressed inside it; one year spent outside is equal to 2000 years inside. If the Kōryū catches you, the effect is lethal. If you are rammed by the Kōtotsu you are thrown out into a different time than the one you walked in from, which explains the time difference at the beginning of the Ryoka Invasion. It was only thanks to Urahara's skills that the time difference was so marginal; a greater time difference is also deadly. Now, since the Kōtotsu is gone, the Dangai is the perfect place to make up some lost time. Since time flows 2000 times faster inside the Dangai, if Ichigo trained inside for 2000 hours, only one hour will have passed outside. Soul Society cannot halt the Kōtotsu, but Isshin can stop the Kōryū, using the Kaikyō Kotei, a device which enables Shinigami to stabilize the Kōryū. Isshin will stabilize the Kōryū until his Reiatsu is depleted. He says he'll be able to last about 2000 hours, akin to three months. Ichigo must use this time to get his Zanpakutō to tell him about the Final Getsuga Tenshō. Ichigo assumes a meditative position with his sword laid across his knees. To test his concentration, Isshin tries whacking him over the head, proving he wasn't concentrating hard enough. Ichigo apologizes and says he never used this technique to commune before. As he resumes his previous position, Isshin explains that it is called Jinzen, a technique refined over millennia to enable communication with one's Zanpakutō. The techniques that Ichigo has mastered so far have all been taken by force. Now, in order to proceed, Ichigo must experience all those thousands of years he has never touched before.

Ichigo's Friends Awaken
Keigo finds himself all alone in the streets of Karakura Town, with everyone else around him sound asleep. He begins to panic and runs, crying through the slumbering streets, calling for someone to wake up. Suddenly, he is clothes-lined by someone and goes down. Looking back he sees his classmate, Tatsuki Arisawa. In his relief for seeing her, he begins ranting and doesn't stop until she punches him in the face and tells him to shut up. He begins apologizing and Tatsuki yells at him, telling him to be quiet and follow her. She takes him to where she found Michiru Ogawa and Chizuru Honshō and tells him to carry Chizuru. Keigo loads Chizuru on his back and Tatsuki warns him against touching her butt. Keigo denies having such intentions, but seconds later informs her that Chizuru's breasts are bigger than he imagined, earning him another punch in the face. Tatsuki says she patrolled the outskirts of the town and found that it just cuts off with nothing, but mountains beyond it. She says she thinks the entire town has been transported to another world. Keigo asks if she thinks it has something to do with Ichigo. Tatsuki replies that she's sure of it, but that she is equally sure Ichigo will put things right, since that's the kind of person he is. As Aizen reaches the edge of Karakura Town, he comments on how unsightly its image is. In the Dangai, a spray of blood from Ichigo's shoulder tells Isshin his son has succeeded in performing his Jinzen.

Introducing: Tensa Zangetsu
Ichigo opens his eyes and finds that he is underwater. He frantically tries to make it to the surface, but his robe is caught by the hand of a mysterious assailant and he is thrust against the roof of a building. The stranger floats above him as Ichigo struggles to breathe; he tells him to relax and breathe normally and Ichigo is surprised to find he can breathe freely. Ichigo asks the stranger who he is, since only Zangetsu is meant to be in his inner world. The stranger remarks that it is a very rude way on Ichigo's part to address the person who taught him how to breathe. After saying that, he materializes Tensa Zangetsu out of the thin air. As the man removes the hood covering his face Ichigo is amazed to see before him a young man with bright eyes and long black hair. The young man says it's no surprise Ichigo can't recognize him, as it is the first time he has entered his internal world while in Bankai. With those words the young man attacks. Ichigo blocks and asks him if he is Zangetsu. The man denies and asks Ichigo what the name of his Bankai is. He then introduces himself as Tensa Zangetsu.

In the Dangai Isshin sees the physical toll Ichigo's body takes as a result of his internal struggle and states that Zangetsu will be violent this time. He adds that his Engetsu was the same; the Zanpakutō are reluctant to teach them this technique - Ichigo will soon learn why. Ichigo asks Zangetsu to hold up, saying he hasn't come there for a fight this time; he just needs to ask a question. Zangetsu guesses Ichigo has come to ask about the Final Getsuga Tenshō. While Ichigo is surprised, Zangetsu swings his sword in a way that nearly decapitates Ichigo, who dodges it at the last split second. When Ichigo confronts him, Zangetsu maintains he cannot teach Ichigo that technique; Ichigo retorts that he cannot leave without learning it. He must know it in order to protect Karakura Town. Zangetsu grabs Ichigo's arm, stopping his unresolved assault. He says he doesn't care what'll happen to the things Ichigo wishes to protect. He swings his sword, landing a hit on Ichigo and pushing him against another building. He tells Ichigo they have different agendas when it comes to the thing they wish to protect.

Welcome to Karakura Town
A Karakura Town citizen, dazed and confused after waking from his forced sleep, finally sees another person up and about - Sōsuke Aizen and Gin Ichimaru. He approaches them and asks if they know what happened. Aizen ignores the man's question and warns him to stay away. As he passes next to the man, about a quarter of the man's body dissipates and he falls lifeless to the ground. Aizen explains that normal Humans cannot sense his Reiatsu, but their bodies cannot withstand its presence. A trail of dead Humans marks Aizen's passage through Karakura Town.

Tensa Zangetsu Shows Ichigo the Truth
In his domain within Ichigo's inner world, Zangetsu effortlessly holds off Ichigo. Ichigo asks him what he meant when he said he didn't care about the things Ichigo wanted to protect. Ichigo says he thought Zangetsu was lending him his power to aid him in his cause. He asks Zangetsu what was his real motivation in helping him thus far. Zangetsu replies that he meant exactly what he said. He turns Ichigo's attention to the world around them and the changes it has undergone: Where once stood proud skyscrapers that pierced the hopeful heavens, now stands a faded replica of Karakura Town; the rain stopped, but instead the entire world has become submerged. The reason for these changes is that Ichigo has succumbed to his despair and ceased moving forwards. Zangetsu surprises Ichigo by suddenly appearing next to him. He lunges his hand into Ichigo's chest and tells him he won't allow him to go on this way - he will remove the source of Ichigo's despair right then and there. Zangetsu pulls and removes an alien object from within Ichigo's body, along with a great amount of blood. As Ichigo looks on, he sees that the object pulled out of him is a strange looking Hollow with a black horned mask. The Hollow greets Ichigo in a coarse manner and then asks him why he is so astonished, since he should recognize him. The Hollow removes his mask to reveal himself as Ichigo's inner Hollow.

Aizen's Confrontation
While walking through the streets, Tatsuki suddenly asks Keigo if he wasn't going to look for Mizuiro Kojima. Keigo replies that he has, more or less. He says ever since Ichigo's disappearance, Mizuiro has been walking alone to school and he isn't answering his cell phone. Keigo thinks he must still be asleep somewhere. Tatsuki says she thought the two were close, as they've been friends since middle school. Keigo denies it, saying Mizuiro and he have their personal spaces. Mizuiro only ever truly opened up to Ichigo and since he usually builds walls between himself and other people, Keigo was just happy seeing him bonding with anyone. Keigo realizes, all of a sudden, that he's saying much more than is needed and asks to change the subject. Tatsuki agrees, as she found the topic boring. However, she suggests they drop off Chizuru and Michiru over at the school and then head out to search for other people: Keigo would look for Mizuiro while she will try and find Karin Kurosaki and Yuzu Kurosaki, since Ryō Kunieda and Mahana Natsui can take care of themselves and Isshin is probably still sleeping.

The two teenagers' conversation is abruptly cut short, as the sensation of Aizen's Reiatsu hits them. The Reiatsu's effect paralyzes Tatsuki, but she tells Keigo not to worry about her. As Aizen and Gin draw near, Tatsuki falls to her knees. Aizen commends the Humans for staying alive while being this close to him. Tatsuki asks Aizen who he is. Instead of an answer, Aizen states that Ichigo will soon be coming, wielding a new power. He wishes to advance the perfection of that power and killing Ichigo's friends would serve that purpose. Hearing this, Tatsuki orders Keigo to run. When he lingers she presses on him, asking if he thinks he can do any good standing there. Seeing the truth in her words, Keigo turns away and runs with Chizuru on his back. Gin intends to pursue Keigo, but Aizen tells him there is no need - they will simply start with Tatsuki. As Tatsuki frantically tries thinking up a game plan, a mysterious shadow approaches behind her back.

Ichigo's Power: Tensa Zangetsu & the Inner Hollow
Ichigo is surprised to see the Hollow, as he believed he destroyed him during their last encounter. The Hollow reminds him of what he said: if he wants to control his Hollowfication, he'd better stay alive until the Hollow appears again. Ichigo swears and says he thought he defeated the Hollow for good. The Hollow sarcastically apologizes for disappointing Ichigo. Changing the subject, Ichigo inquires about the Hollow's new appearance. Zangetsu replies that this form was the one Ichigo took as he defeated Ulquiorra Cifer. Ichigo is shocked to learn this, but Zangetsu explains that Ichigo was so frightened of this form, he was unable to Hollowify properly. Ichigo asks if he should fight the Hollow again, but Zangetsu and the Hollow both reply that his opponent will not be either of them, but both of them. Before Ichigo's shocked eyes, the two figures disintegrate and merge into one. The merged Zangetsu says they were at first two beings as one; both of them were Ichigo's power. The newly formed being challenges Ichigo and attacks.

Don Kanonji, to Save the Day
Tatsuki, bewildered and petrified by Aizen's proximity, finally comes to the conclusion that she must let go of Michiru if she wants to defend herself; however, she is unable to move. Aizen's upper body is suddenly engulfed in an explosion of energy. The explosion was the result of Don Kanonji's Kanon Ball. Kanonji himself lets his presence be known. He tells Tatsuki she appears to be in trouble and in times like these the need arises for a hero. He then begins his introduction with his catchphrase: The spirits are always with you; apologizes to all his fans for being late, but says that he, Don Kanonji, has now returned. Tatsuki and Gin both look at him perplexed and Aizen, when the smoke from the Kanon Ball clears, asks him who he is. Kanonji is quite annoyed to meet a person who can't recognize him, but his narcissistic nature demands he introduces himself again. Tatsuki destroys this plan by asking him what he is doing there, calling him by name. Since she ruined his introduction, Kanonji asks her if she is a demon. Tatsuki ignores him and just tells him to run away since there is nothing he can do to help. At that moment, Kanonji senses Aizen's Reiatsu for the first time.

Rangiku Arrives on the Defense
Aizen remarks that Kanonji is on the border of withstanding his Reiatsu, but says perhaps he should congratulate him for withstanding it for so long. Tatsuki urges Kanonji again to run away, but he explains to her that he is a hero and the children will never respect a hero who runs away. He wields his Spirit Stick and charges at Aizen. Aizen tells him to stop, warning him that if he touches him he would die. When Kanonji jabs at Aizen with his stick, the stick begins to disintegrate. Suddenly, Kanonji is grabbed and pushed aside by a blonde woman in Shinigami uniform. The woman is Lieutenant Rangiku Matsumoto of the 10th Division. She states she has arrived in the nick time and faces Aizen and Gin. Kanonji recovers from his surprise and demands to know who Rangiku is. He tells her this place is too dangerous for normal people; he insists she stands back and let the Hero take care of things. Rangiku ignores him and tells the Humans to run away and leave Aizen and Gin to her. When Kanonji begins to protest she grabs his face and resorts to threatening him with bodily harm if he doesn't pick up Tatsuki and Michiru and take them out of harm's way. Kanonji complies with this order, but before leaving tries to save face by telling her to call on him if she needs assistance. Rangiku tosses a soda can at him and Kanonji departs. As she is carried on Kanonji's back, Tatsuki wonders who Rangiku is. She is upset that Ichigo never told her he met such a beautiful woman.

Secret of the Final Getsuga Tenshō
In his inner world, Ichigo is thrown against a building by one of Zangetsu's thrusts. His hair has grown much longer during the extended battle and he has lost a lot of blood. Zangetsu asks him if he can still stand, to which Ichigo replies he told him he would not fall until Zangetsu divulges the secret of the Final Getsuga Tenshō. Zangetsu retorts that he said he didn't feel like telling it. Zangetsu attacks, but Ichigo realizes Zangetsu doesn't want to kill him or he would do so at the beginning; and if he was serious about not telling him anything, he could have just avoided the fight entirely. Ichigo can only feel loneliness flowing from Zangetsu's sword. Ichigo repels a few more attacks, but when Zangetsu charges again, he lets go of his swords and absorbs the attack. With his sword piercing through Ichigo's chest, Zangetsu tells Ichigo he has realized at last that in order to learn the Final Getsuga Tenshō, he has to accept Zangetsu's sword. Ichigo feels no pain from the strike and Zangetsu remarks that it's obvious, since Zangetsu is a reflection of him. Zangetsu begins to weep and when Ichigo asks him why he cries Zangetsu reminds him of what he said at the beginning of the fight, about the both of them wanting to protect different things. Ichigo says he remembers and Zangetsu says what he wanted to protect was Ichigo. Ichigo asks him to explain, but Zangetsu says the sword would answer that and reveal the secret of the technique.

Aftermath
Aizen contends against unforeseen foes and ones he had anticipated who would come face him.