Bankai Training

 is an event taking place over the course of the last three days of the Ryoka Invasion's central conflict: unable to defeat 6th Division Captain Byakuya Kuchiki and rescue Rukia Kuchiki at his current level of power, Ichigo learns of the existence of a rare secondary release for Zanpakutō known as Bankai and begins training to achieve it before Rukia's execution by using a dangerous but efficient process. During this period, the other Ryoka around the Seireitei find themselves in unexpected situations, and 6th Division Lieutenant Renji Abarai eventually joins Ichigo in his Bankai training for his own purposes.

Prelude
After Ichigo Kurosaki finishes battling 11th Division Captain Kenpachi Zaraki, Rukia Kuchiki stands on the bottom floor of the Shishinrō within Senzaikyū realizes that the sounds outside have vanished alongside the two Reiatsu she felt earlier before noting that she cannot tell which combatant died due to the Sekkiseki walls around her blocking and scattering Reiatsu. Questioning why blood has been shed for her and if she is really worth it, Rukia asks Kaien Shiba what he would say about the matter.

Shortly afterward, on the walkway connected to the bridge outside Senzaikyū, one of the guards expresses relief at the intense Reiatsu finally dying down and notes that the fight demolished the eastern half of the compound as he wonders if the cells inside were damaged in the process. When the other guard teases him as being pathetic for being shaken by the Reiatsu all the way over here, the first guard points out that he is also shaking and is pathetic as well.

Suddenly, as he demands to know why he is considered pathetic, the second guard has a few drops of Shinten poured on his forehead by 4th Division 7th Seat Hanatarō Yamada, causing him to collapse, and as the first guard sees Hanatarō retreating on the roof above and prepares to pursue him, Ganju Shiba drops down behind him and elbows the guard in the face, sending him rolling back along the walkway.

Climbing down from the roof with the rope attached to Ganju's grappling hook, Hanatarō chastises him for being so rough, and when an embarrassed Ganju inquires what kind of drug he used, Hanatarō explains that it is a tranquilizer called Shinten which knocks out those with low Reiryoku with only a drop on the skin. With Ganju unnerved by him carrying around such a thing, Hanatarō questions why he should not do so and assures him that it will not work on strong people. Shortly afterward, Ganju and Hanatarō reach the last door of Senzaikyū, which Ganju observes is a shutter-type. However, as Ganju questions how they will open it, Hanatarō pulls out a large wooden block key from within his shihakushō and reveals that he borrowed it from the cell lock storage room in the canal network last night.

Though he admits that he probably should not have done this, Hanatarō recounts how he was thinking about how he always runs while Ichigo fights so hard, which he does not think is cool, and expresses his desire to save Rukia as well before concluding that he decided to do whatever he could even if he got punished for it later. With Hanatarō brushing this off as useless because all he could do was steal a key, a surprised Ganju asserts that he did more than his share. As they slide the door upward upon unlocking it, Ganju theorizes that Rukia must be very attractive if everyone wants to save her so desperately, though Hanatarō denies this, and cheerfully looks inside the Shishinrō in search of her, only to be mortified upon seeing her in the cell.

While Ganju recalls the Shinigami who brought a dying Kaien to the Shiba Clan household when he was young, Rukia asks him who he is and if he is with Ichigo, prompting Hanatarō to pop out from behind Ganju and express relief at her being alright. When a surprised Rukia wonders what he is doing here, Hanatarō promises to tell her later and begins pulling Rukia by the wrist toward the door as he tells Ganju to hurry because there is no time to waste. However, Ganju remains still in stunned silence, and as a concerned Hanatarō inquires what is wrong, Rukia notices the pattern on Ganju's pants and realizes that he is a member of the Shiba Clan. Upon being asked by a confused Hanatarō if he knows Rukia, Ganju continues to recall the night of his brother's death.

Ganju tensely states that he could never forget Rukia's face before claiming that she is the Shinigami who killed Kaien. Unnerved by this, Hanatarō attempts to assure Ganju that Rukia could never do something like this, but Ganju recounts how Kaien's slit throat and punctured chest were wounds from a sword and not something he would have died from had he fought a Hollow. With Ganju angrily proclaiming that she said she killed Kaien that night, Rukia tells Hanatarō that he is right and reaffirms to Ganju that Kaien indeed died by her hand. Enraged by this, Ganju leaps toward Rukia and grabs her by the collar while she calmly states that she will not stop him from killing her if he wants to do so.

As he pulls on Ganju's free arm, Hanatarō begs him to stop and reminds him that they came here to save Rukia because Ichigo entrusted them with her life. Suddenly, the three of them experience the sensation of a powerful Reiatsu crushing down on them, and as Ganju and Hanatarō turn around to face the doorway in fright, 6th Division Captain Byakuya Kuchiki approaches them on the bridge. Meanwhile, at the Ugendō Quarters in the Thirteenth Division barracks, Captain Jūshirō Ukitake is shocked to learn of 5th Division Captain Sōsuke Aizen's murder, and when asked about the time and motive of this by Ukitake, the Riteitai relaying this to him details how it happened earlier today and neither the murderer nor motive are known, prompting Ukitake to wonder what happened while he was sleeping before asserting that he will get to the bottom of this.

Back on the bridge, when Hanatarō notices that he recognizes Byakuya, Ganju describes him as being a member of the Kuchiki Clan, one of the four highest-ranked noble families, and the most powerful leader in the history of his family as well as the most famous of the Gotei 13 captains. Bemoaning Byakuya showing up at a time like this, Ganju bluntly states that they have no chance of defeating him and nervously proposes begging for their lives in a bid to convince him to let them go. Though a surprised Hanatarō questions what he is talking about and suggests that they run off with Rukia Kuchiki, Ganju points out how there is no way out other than crossing the bridge, which will lead to Byakuya killing them, and angrily demands to know if Hanatarō expects him to risk his life for Rukia.

With a somber Rukia remaining silent, a trembling Hanatarō acknowledges there is no reason for Ganju to fight for Rukia because this rescue was never personal for him before requesting Ganju take Rukia with him while he stops Byakuya, shocking Ganju and Rukia. Upon being asked by a stunned Ganju if he knows what he is doing, Hanatarō affirms this and admits he would do the same thing Ganju is doing if he were in the latter's position due to not wanting to risk his life for an enemy, and when an incredulous Ganju clarifies he is referring to how Byakuya's Reiatsu is at least as powerful as Kenpachi's, which is something neither of them can handle, Hanatarō confirms this, only to note he cannot leave without trying to save Rukia after coming so far in order to do so. Bowing to Ganju, Hanatarō thanks him for everything and hopes that they will meet again while turning and walking onto the bridge toward Byakuya, leaving Rukia to desperately call out to him.

As he holds his arm out in front of Rukia to stop her from following, Ganju observes that Hanatarō does not even have a Zanpakutō and is still visibly shaking in fear before yelling as he walks over to the wall and slams his forehead into it, startling Hanatarō. Walking up to Hanatarō with a bleeding forehead, Ganju orders him to move and kicks him back to Rukia's cell as he turns to face Byakuya. After mentally apologizing to Kaien Shiba because his revenge will have to wait due to Kūkaku Shiba not raising a coward who would abandon a friend, Ganju addresses Byakuya and declares that the latter will have to get past him.

During this, within the Study Chamber inside Sōkyoku Hill nearby, Ichigo sleeps on a mat surrounded by a healing field near the hidden entrance after being brought there by Yoruichi Shihōin, who greets him when he opens his eyes. Though Ichigo attempts to leave so he can help his friends, whom he believes are in danger, Yoruichi insists that he stay in order to recover from his grievous injuries and assures him that the other Ryoka are fine before revealing that Ichigo's life was saved by a Hollow mask in his pocket absorbing the brunt of what would have been a fatal last strike. However, Yoruichi is shocked to learn that a similar mask appeared during Ichigo's fight with 6th Division Lieutenant Renji Abarai and that Ichigo threw it into the river afterward, leading Yoruichi to confiscate it out of concern for what this could mean.

When Ichigo comments on how amazing Yoruichi is, the latter questions this, prompting Ichigo to detail how Yoruichi is unharmed despite the area being patrolled by captains and managed to carry him here with such a small body, only to be told this was not difficult in Yoruichi's original form. Registering what he was just told, Ichigo expresses bewilderment, and after noting that it had been kept secret from Ichigo and his friends all this time, Yoruichi decides to show Ichigo her true form and transforms into a tall, dark-skinned woman, leaving Ichigo speechless with shock. Yoruichi observes that most people assume she is male due to how she sounds in her cat form and mocks the foolish reactions she receives whenever she reveals her true form, which she takes great pleasure in eliciting, before attempting to show Ichigo how she brought him here as she holds up her Ryūkotsujō, only for a heavily blushing Ichigo to demand that she put on some clothes. Apologizing, Yoruichi begins getting dressed while noting that she has not worn clothes in a long time and teases Ichigo about being so prudish when seeing a naked woman.

With a still-blushing Ichigo reiterating his request for her to get dressed as he looks away, Yoruichi inquires if he is sure that he does not want to take this chance due to it possibly being his last opportunity, prompting a flustered Ichigo to declare that this is none of her business. As Yoruichi criticizes his sense of humor and claims that other people must consider him boring, Ichigo claims that this is not the case as he realizes that Yoruichi is not wearing pants and reminds her that she is supposed to get dressed from the bottom up. After getting fully dressed, Yoruichi holds up the Ryūkotsujō she used to transport Ichigo here and asks him if his stomach wound is better before observing that he likely made it worse by screaming so much.

After clutching his bleeding abdomen and mentally calling Yoruichi a jerk, Ichigo examines the Ryūkotsujō and reiterates Yoruichi's explanation of it allowing the user to fly when filled with Reiryoku, and when Yoruichi proudly describes it as a rare and valuable artifact even within Soul Society, Ichigo notes that she still managed to acquire it and lists off Yoruichi's healing prowess, ability to change forms, and possession of unusual artifacts as he questions just who she is. However, as a surprised Yoruichi begins to explain, she and Ichigo suddenly experience the crushing sensation of Byakuya's Reiatsu, leading Ichigo to recognize it as belonging to the man who destroyed his Shinigami powers and took Rukia from the Human World.

When Yoruichi realizes that it is coming from Senzaikyū, Ichigo grabs his Shikai, Zangetsu, and begins running off. Upon being asked by Yoruichi what he plans to do, Ichigo asserts that he has to save Ganju and Hanatarō, who were headed to Senzaikyū, because no one else will before channeling his Reiryoku into the Ryūkotsujō, causing a large bat-like wing to unfurl as the Ryukotsujō wraps itself around his arm and propels him into the air, leaving Yoruichi to angrily call him a fool. Back on the bridge leading to Senzaikyū, Byakuya continues to exert his Reiatsu as he recounts how he came to see what terrible foe had gained entry to the cell by concealing its Reiatsu upon sensing someone moving toward this location, only to conclude by expressing his disappointment at merely finding a bug present instead.

Far behind Ganju, Rukia attempts to run after Ganju and stop him despite Hanatarō's protests, but ends up collapsing, leading her to realize that her body will not move the way she wants it to after losing so much Reiryoku from being kept in her Sekkiseki cell for the past several days. Despite this, Hanatarō assures her that Ganju likely has a brilliant plan in mind due to how confidently he confronted Byakuya. Despite this, after mentally observing that it would be a waste of time to use his usual tricks against someone as strong as Byakuya given how intense his Reiatsu is, Ganju decides to take his chances and rushes at Byakuya with his cleaver drawn, leaving Rukia and Hanatarō to express shock at him actually not having a plan after all.

Suddenly, as Ganju attempts to use his "Tears of Blood" smoke bombs, Byakuya appears behind him and tells Ganju to disappear because his sword is not for crushing vermin while Ganju finds his left arm slashed from his shoulder to his inner elbow, causing blood to spurt into the air as Ganju screams in pain. Hanatarō calls out to him in concern as Byakuya continues approaching him and Rukia, but Ganju demands that Byakuya stop. When Byakuya reiterates his order for Ganju to disappear, Ganju asserts that he does not care if Byakuya is a famous noble. Upon hearing Ganju proclaim that the Shiba Clan does not produce cowards who run away from fights so easily, a surprised Byakuya apologizes for dismissing him and promises that Ganju will not leave here alive for being a Shiba as he draws his Zanpakutō. With Ganju wondering what Byakuya plans to do from such a distance and Rukia pleading with him to not do this, Byakuya releases his Shikai, Senbonzakura, causing the blade of his Zanpakutō to separate into a thousand slender blade petals. While Rukia screams at him to run, a stunned Ganju is slashed in multiple areas of his body at once by the blade petals, leaving him to collapse in a heap on the bridge as he loses consciousness and a large amount of blood.

Seeing a petrified Hanatarō watching this, Byakuya turns to him and raises his Zanpakutō handle to attack once more despite Rukia moving between the two of them and begging him to stop, only for Ukitake to appear behind him and grab his wrist before he can follow through. As he comments on how dangerous it is around here, Ukitake tells Byakuya he has done enough, and when Rukia calls out to him in astonishment, Ukitake kindly greets her while observing she has lost weight and inquiring how she has been. Upon being asked by Byakuya what he is doing here, Ukitake claims he should be the one asking this question and points out how there is a ban against drawing one's Zanpakutō even if it so one can drive off Ryoka.

Byakuya merely informs Ukitake that there is a wartime exemption permitting this in effect, leaving Ukitake incredulous at such a measure being taken over the appearance of a few Ryoka as he questions if Aizen was killed by one of them. However, both Ukitake and Byakuya are shocked upon sensing a powerful Reiatsu approaching their location, and as Ukitake describes it as being captain-level despite not recognizing it, Hanatarō realizes who it belongs to as Rukia sees Ichigo hurtle from under the bridge into the air above her with the aid of the Ryūkotsujō. Landing in front of Rukia while the others watch in astonishment, Ichigo walks past her as she attempts to address him and apologizes to Hanatarō for sending him and Ganju ahead as Hanatarō tearfully recounts what has happened. As he acknowledges this, Ichigo turns to Rukia and declares that he has come to rescue her.

With Rukia remaining silent, Ichigo questions why she is not at least smiling after he came all this way to help her, only for an emotional Rukia to remind him that she told him to not come after her and point out how injured Ichigo is. Despite this, Ichigo merely acknowledges that he is an idiot, and as he looks over Ganju's bloody form, Ichigo gives Rukia permission to yell at him as much as she wants after he beats Byakuya. With Ichigo staring down Byakuya, Rukia calls out to him as she stands nearby, prompting Ichigo to question if she intends to tell him to give up and assert that Rukia is coming with him even if she wants to be executed.

When Ichigo declares that he is rejecting all of her protests, Rukia is flabbergasted by Ichigo deciding to ignore the wishes of the person he is saving and demands to know what kind of tyrannical rescue this is, prompting Ichigo to claim that he does not want to hear any snide remarks from the one who needs rescuing as he instructs her to find a corner where she can tremble and beg for help. After staring at Ichigo in mutual irritation for a few seconds, a smiling Rukia observes that Ichigo has not changed at all and still does not listen to her. Questioning why he would, Ichigo notes that Rukia always worries about him and should worry about herself instead. With Ichigo assuring her that he will not get himself killed because he has gotten stronger, Rukia recalls Kaien smiling and closes her eyes sorrowfully.

Meanwhile, as he stares in shock at Ichigo, Ukitake asks Byakuya who he is, leading Byakuya to assure him that Ichigo is not related to the one Ukitake is thinking of and is just a nobody Ryoka. Byakuya declares that he will dispose of Ichigo and allow this trifling conflict to come to an end, and as he begins approaching, Ichigo comments on Byakuya's arrogance in not attacking while he and Rukia were talking. After wondering who Ichigo thinks he is speaking to, Byakuya inquires if the former thought Byakuya would attack while his guard was down and criticizes Ichigo's confidence before exerting his Reiatsu, causing Rukia to fall to her knees.

While Rukia and Hanatarō affirm with each other that they are okay, Ichigo draws Zangetsu as Byakuya observes that he has improved from when they last met if he can remain unfazed within such Reiatsu. Though he admits that he is uncertain of how Ichigo regained his Shinigami powers, Byakuya asserts that he should have enjoyed a peaceful life in the Human World because coming here to lose the life that Byakuya spared was foolish. However, Ichigo states that he does not plan on losing it and proclaims that he will be going home after he beats Byakuya, who reiterates his criticism of Ichigo's confidence once more as he disappears from view with Shunpo. With Rukia remembering Byakuya using Senka against Ichigo in their previous encounter, Byakuya attempts to attack Ichigo from behind with his Zanpakutō, but Ichigo intercepts his stab with Zangetsu at the last second and notes Byakuya's criticism of his confidence before grinning as he tells a stunned Byakuya that he can see him and repels his attack, pushing Byakuya back.

As he looks at Ichigo, Byakuya once again comments on his improvement and holds his Zanpakutō in front of him while promising to demonstrate the difference in their skills before Ichigo can drown in his newfound strength, as the latter could not beat him in a thousand years. With Rukia screaming at Ichigo to run, Byakuya attempts to release Senbonzakura once more, only for Yoruichi to appear and bind the entire blade in cloth before he can finish, leaving those present stunned by her arrival. Elsewhere, as he rests in his cell with his arms restrained, Renji is confronted by his Zanpakutō Spirit, Zabimaru, who criticizes Renji for still being asleep.

While Renji expresses annoyance at this being the only thing Zabimaru has to say after all this time, Zabimaru asserts that they are fully recovered and ready to fight, meaning that it is Renji's turn to get better so they can fight Zangetsu once more, which Zabimaru declares they will beat next time. However, Renji reveals that Ichigo is not his enemy anymore, and as a surprised Zabimaru acknowledges this and questions who Renji's enemy is now, Renji merely stares out the barred window next to Zabimaru. Back on the bridge, Yoruichi stands between Ichigo and Byakuya. When Hanatarō wonders who she is, Rukia expresses recognition of Yoruichi's name and identifies her as the former Commander-In-Chief and Corps Commander of the Onmitsukidō.

While Byakuya admits that he thought Yoruichi was dead after not hearing of her for over a century, Ichigo thanks Yoruichi for coming to help him, only to request that she stay out of this because he has to defeat Byakuya. However, Yoruichi dismisses the idea of this being possible and moves over to Ichigo with Shunpo before jabbing her hand into his stomach wound, shocking those present. With a confused Ichigo collapsing, Yoruichi catches and hoists him over her shoulder, prompting Ukitake to observe that she shoved a powerful anesthetic like Gaten or Hōten directly into his organs as he questions if she intends to heal him. When Byakuya declares that he will not allow this and that she cannot escape from here, Yoruichi inquires if he considers himself to be her equal and if he has ever once beaten her in a game of tag, which leads Byakuya to suggest that they give it another try as he and Yoruichi disappear with Shunpo. Upon seeing Yoruichi appear behind him, Byakuya turns around and slashes at her with his Zanpakutō, only to discover she is gone.

However, as Yoruichi reappears on the far end of the bridge behind Ukitake and lands, Byakuya appears behind her and mocks her for believing that she could outrun him with such mediocre Shunpo before slashing her across the chest, severing her left arm in the process. Suddenly, Yoruichi's falling body transforms into a cut piece of fabric as the real Yoruichi lands on a stunned Byakuya's outstretched arm and mocks him for believing that he could stop her with such mediocre Shunpo. After moving to the roof of a nearby building, Yoruichi promises to make Ichigo stronger than Byakuya in three days, and as she declares a truce until that point while acknowledging how self-serving it is, Yoruichi proclaims that she will not be captured before disappearing.

As Yoruichi leaps across the Seireitei with an unconscious Ichigo over her shoulder, Ukitake observes that they got away, and when Byakuya walks away from the bridge, Ukitake questions where he is going and what should be done about the Ryoka on the bridge. With Byakuya claiming to have lost interest and giving him permission to do as he wishes with them, a confused Ukitake comments on his moody nature while Rukia suddenly collapses behind him, to Hanatarō's concern. Ukitake realizes that Rukia must have been concentrating the whole time Byakuya was here and calls out his 3rd Seats, Sentarō Kotsubaki and Kiyone Kotetsu, who leap up onto the bridge and kneel in front of him as Hanatarō assumes they are new enemies. Upon being asked by an unnerved Ukitake how long they have been here after he notes that they followed him, Sentarō reveals that they have been present since Ukitake first arrived on the bridge.

When Ukitake reminds them that he instructed them to not follow him because it was dangerous, Sentarō proclaims that his undying respect for Ukitake would not allow him to idly sit by, prompting an irritated Kiyone to assert that this is also true for her and that she respects Ukitake more than Sentarō does. While Sentarō and Kiyone begin to argue over this claim, an embarrassed Ukitake orders Kiyone to contact the Fourth Division and have them send an advanced rescue unit for Ganju, surprising Hanatarō, before telling Sentarō to put Rukia back in her cell. Though Hanatarō attempts to stop him, Sentarō angrily tells him to move aside and denies wanting to do this, intimidating Hanatarō. Gently picking up an unconscious Rukia, Sentarō assures her that he and Ukitake will get her out of her cell by talking to the higher-ups as he carries her back into the Shishinrō, leading Kiyone to declare that she is more worried about Rukia than Sentarō is and that she will be the one to get her out with Ukitake.

With Sentarō and Kiyone continuing to argue as Kiyone prepares to contact the Fourth Division, Hanatarō approaches Ukitake, who observes that he is probably wondering why Ukitake is letting him live, which a surprised Hanatarō confirms. As he questions why he would not, Ukitake points out how they still do not know who killed Aizen, which the Ryoka may have information about, and thus he could not kill Hanatarō until this has been investigated, but clarifies that Hanatarō attempting to save one of his subordinates is more important to him even if it was through questionable means and promises that he will not stand by and watch Hanatarō get killed.

Later, Yoruichi enters a hidden room within the Study Chamber inside Sōkyoku Hill and drops Ichigo on the ground as she pants heavily while carrying Zangetsu on her back. Noting that she became this exerted after only performing a few hundred consecutive Shunpo movements due to being out of action for one hundred years, Yoruichi claims that she is getting old. After wrapping Ichigo in a blanket, Yoruichi sits against the wall across from him and urges him to wake up due to his need to get stronger before promising to discuss the true power of Zangetsu with him once he does.

Day One, August 5th
After regaining consciousness, Ichigo grabs Yoruichi by the collar and slams her against the wall as he demands to know why she removed him from the confrontation even though he had the best chance of survival of anyone there. With Ichigo claiming Rukia, Ganju, and Hanatarō are going to get killed now, Yoruichi questions his confidence in his power and coldly asserts no one present could have fought Byakuya and lived before flipping a belligerent Ichigo onto his back with Taketonbo, leaving him gasping for air. As she instructs Ichigo to stop shouting so he does not reopen his wounds, Yoruichi states carrying him away was the best she could do.

With Yoruichi concluding that this was the only way to escape Byakuya, Ichigo inquires why she took him and not Rukia, which Yoruichi acknowledges before reiterating that no one there had any hope of defeating Byakuya, only to reveal that Ichigo might have a chance the others would not in three days, making him the only logical choice. Ichigo stares in astonishment as Yoruichi points out how Ukitake was also there and assures Ichigo that he will imprison but not kill Ganju and Hanatarō due to being a very dutiful man. Concluding that they will be alright, Yoruichi states that Ichigo only needs to concentrate on becoming stronger now and promises to train him for three days so that he can defeat Byakuya and save his friends with his own hands.

Some time later, as she stands with Ichigo in the central, rocky cavern of the Study Chamber, Yoruichi notes that they do not have time for him to heal completely and that Ichigo will have to endure the pain he is in. While Ichigo draws Zangetsu, Yoruichi asks him if he is aware that Zangetsu is a constant release-type Zanpakutō, prompting a surprised Ichigo to realize that she is referring to the classification that Kenpachi's Zanpakutō falls under and admit that he always knew Zangetsu was different from others since it never changes shape even if he calls its name as Yoruichi observes that he also does not know that Zangetsu has a second stage of release.

Ichigo can only stare in astonishment as Yoruichi details how all Zanpakutō have two stages of release, Shikai and Bankai, before revealing that it is mandatory for a captain to be able to perform both. Clarifying that this means every captain has mastered Shikai and Bankai with one exception, which is Kenpachi himself, Yoruichi explains how Kenpachi is the only Shinigami in the history of Soul Society to become a captain without being able to perform Bankai or even knowing the name of his Zanpakutō due to his immense fighting prowess and elaborates that a Zanpakutō's Bankai is generally five to ten times stronger than its Shikai is.

Though Ichigo is further shocked by this, Yoruichi admits that this power difference requires at least ten years of training to fully master even for someone with great talent. With Ichigo reminding her that he does not have this much time, Yoruichi acknowledges this and clarifies that she is referring to normal training before revealing that she is taking a completely different approach for Ichigo that, despite the great risk it carries, will allow him to learn Bankai in three days. At 11:33 AM, when Yoruichi brings out the Tenshintai, a confused Ichigo inquires what it is, leading Yoruichi to explain that the Tenshintai is a vital spiritual tool of the Onmitsukidō that can externalize a Zanpakutō Spirit.

With Ichigo perplexed at the idea of needing this to achieve Bankai, Yoruichi confirms this and elaborates that while the essence of Shikai is communicating and synchronizing with one's Zanpakutō Spirit, Bankai requires externalizing it and forcing it into submission, which means that one must summon their Zanpakutō Spirit to the real world instead of entering their inner world to communicate with it, a move which usually takes ten years of training to perform. However, Yoruichi asserts that she believes Ichigo is ready to externalize Zangetsu after fighting Kenpachi, leading Ichigo to remember Zangetsu appearing before him during that battle.

After observing that Ichigo knows what she is referring to, Yoruichi details how Ichigo piercing the Tenshintai with Zangetsu will force this to happen and how she will use her power to maintain it, but concludes that it can only be done once and lasts for three days, meaning that Ichigo must somehow force Zangetsu to submit in this time. Ichigo interrupts Yoruichi by stabbing Zangetsu into the Tenshintai and declares that he will not ask her what happens if he fails because he will simply have to do this if it is the only way. As the Tenshintai shatters and Zangetsu disappears, Zangetsu appears next to a surprised Ichigo and notes that he seems to have recovered. Confirming with Zangetsu that he heard the explanation, Yoruichi gives him permission to choose the method of battle and requests that he start immediately, prompting Zangetsu to kneel and place his hand on the ground before manifesting dozens of Zangetsu-like swords in the surrounding area.

With Ichigo staring in astonishment, Zangetsu clarifies that only one of these real swords represents the real him and is the only one which can defeat him, meaning Ichigo must find it and use it to defeat Zangetsu before the latter kills him. At 12:01 PM, Yoruichi stands over Ichigo, who is lying on the ground with a bleeding head wound, and orders him to get up due to still having a long way to go. Yoruichi instructs Ichigo to get up because there is no time to lose, and as he struggles to stand up, Zangetsu promises to drag him to his feet if he does not get up on his own as he stands before Ichigo with a variant of Zangetsu, that has spines arcing off the blade.

Hearing this, Ichigo leaps back as Zangetsu does the same in the opposite direction, and after grabbing separate swords, the two of them clash fiercely while Yoruichi watches. Meanwhile, Renji incapacitates the guard outside his cell and destroys several of the bars before stepping through as he tells Zabimaru that they are going. Elsewhere, in the Fourth Division's Sōgō Kyūgo Tsumesho, a handcuffed and bandaged Uryū Ishida wakes up on a cot in the 75th underground relief cell and wonders where he is while realizing that he is still alive. Suddenly, a heavily bandaged Ganju looks over the side of the cot above Uryū's and greets him, only for Uryū to scream in confusion upon seeing Ganju's completely bandaged face.

With a shocked Uryū demanding to know if he is a burglar, Ganju leaps down from his cot and questions what he would steal from an invalid in a jail cell as he lifts his bandages to expose his eyes and mouth so Uryū knows who he is. Relieved to learn that it is Ganju, Uryū admits that he was worried about the former because he did not seem very strong, prompting an annoyed Ganju to claim that he felt the same way about Uryū. When Uryū asks Ganju why the Shinigami would treat their injuries when the Ryoka are intruders and their enemies, Yasutora Sado reveals that there has been a new development, leading to Uryū look over to see him sitting nearby.

Sado details how he heard the guards discussing the murder of one of the Gotei 13 captains inside the Seireitei, which leaves them as prime suspects for being Ryoka. As Uryū concludes that they are being kept alive for questioning, Ganju affirms this and notes that he could get them out of here with Seppa were it not for his handcuffs being made of Reiryoku-sealing Sekkiseki. Uryū looks down at his handcuffs and mentally observes that even without his handcuffs, he would not have access to his powers anymore due to his usage of the Quincy: Letzt Stil. Despite this, Ganju points out that their friends are probably still alive if the enemy does not want them dead.

After stating Orihime has probably been captured as well due to her lack of combat skills if they are in here, which leaves Ichigo and Yoruichi, Sado asserts he is going to wait for Ichigo because the latter will definitely come here before telling Ganju and Uryū all they can do until then is recover from their injuries and prepare for the next fight. Back in the Study Chamber, the last sword Ichigo picked up is shattered by the sword Zangetsu is wielding, sending Ichigo skidding back with a broken hilt in his hand. Cursing this, Ichigo throws the hilt away as Zangetsu notes this is the eighteenth sword Ichigo has gone through and chases after Ichigo when the latter leaps away.

Upon seeing a sword identical to Zangetsu embedded in the ground nearby, Ichigo moves to it and pulls it out while claiming that only the real Zangetsu would be shaped like this. However, Zangetsu shatters it with his bare hand when Ichigo swings it at him, and as Ichigo stares in stunned silence, Zangetsu proclaims that this was feeble before slashing Ichigo across the chest with his own sword. Zangetsu reminds Ichigo that all of the blades embedded in the ground here are pieces of his spirit, with this being a test to find the piece made for fighting, and that the sword he just broke was a piece of Ichigo's fragile spirit trying to rely on Zangetsu, leading him to assert that Ichigo should not even speak of Bankai until he can tell the difference. With Zangetsu ordering him to try again because he does not have time to be resting on his knees, Ichigo picks up another sword and declares that he knows this while Yoruichi watches from afar.

Meanwhile, in the Eleventh Division barracks, Makizō Aramaki proclaims his happiness at being unexpectedly picked up by Lieutenant Yachiru Kusajishi, who sits against the wall nearby as she explains how Orihime's Reiatsu was similar to Ichigo's due to them both being Ryoka and how she simply found Aramaki nearby when she went to investigate. With Yachiru struggling to remember his name, Aramaki introduces himself as Maki-Maki and comments on how it has already been ten years since he joined the division, only to be shocked when Yachiru calls this a silly name because she gave it to him herself. While Orihime sits on a chair nearby, 3rd Seat Ikkaku Madarame lounges on a couch against the far wall and inquires if she thinks Ichigo is still alive, though Orihime admits that she is not sure. Telling Ikkaku to not ask stupid questions, a heavily bandaged Kenpachi claims that he knows Ichigo is alive and sits in front of Orihime as he promises to help her because he has a feeling that he will see Ichigo again if he sticks with her.

Soon afterward, half of a broken Zangetsu-like sword embeds itself in the ground as a wounded Ichigo skids to a halt with the remainder of the sword in hand while his blood spatters on the rock behind him. Watching from above, Yoruichi observes he is still holding his stance even after his sword is broken, and as Zangetsu notes this makes fifty-one broken swords, Ichigo tosses away the broken sword and pulls a serrated one out of the ground next to him before rushing toward Zangetsu, who swings his hooked sword horizontally at Ichigo. Though he initially blocks perpendicularly with his own sword, Ichigo tilts his blade toward himself and ducks to allow Zangetsu's sword to swing over him as a surprised Zangetsu completes his swing.

Ichigo stabs his own sword at Zangetsu, only for the latter to leap high into the air before the strike reaches him, leaving Ichigo to shatter the rock behind where he was standing. With Ichigo looking up in shock, Zangetsu throws his own sword directly downward, shattering Ichigo's sword on impact and sending a large chunk of the blade flying away. Zangetsu appears in front of a stunned Ichigo and backhands him into a rock several meters away as he admonishes Ichigo for taking his eyes off the enemy and notes that this makes fifty-two broken swords. While a smiling Ichigo admits that he thought he finally had Zangetsu, Yoruichi mentally details how Ichigo deflected Zangetsu's initial attack at the point of contact by matching the speed of his own sword with that of his opponent before instantly going on the offensive.

Observing Ichigo has come a long way from relying solely on Zangetsu's strength and is now learning at a frightening pace and level, Yoruichi mentally tells Kisuke Urahara he was right about Ichigo. Some time later, Ichigo wields a scimitar-like sword clashes fiercely and repeatedly with Zangetsu, who wields a jagged sword, and as Yoruichi watches from above, Ichigo and Zangetsu are sent flying apart by the force of their clash, prompting Yoruichi to observe Ichigo has been fighting for more than five minutes with the same sword without it breaking, though she begins sweating and notes it could be near its limit while the loop of cord in her hand glows with Reiryoku.

With Ichigo declaring that he is not done yet and rushing toward him, Zangetsu moves to attack, only to disappear and send his sword flying as the Tenshintai he was inhabiting returns to its normal state, leaving Ichigo speechless in confusion. Landing behind Ichigo, Yoruichi tells him drop his sword because the first day is over as she undoes her ponytail. Shortly afterward, a naked Ichigo relaxes in a hot spring behind a rock in the training area and admits that he had no idea it was here while realizing that he has never been in one before. After observing that it must be nighttime if the first day of training is over, Ichigo states that he can feel his joints creaking and that his sense of time is messed up down here as he splashes water on his face.

Suddenly, Ichigo finds the scratch on his face rapidly healing upon coming in contact with the water, leading him to express awe and excitement at his discovery of how the hot spring actually heals his wounds rather than simply removing the pain. As Ichigo slurps some of the water into his mouth in an attempt to heal the cut inside, Yoruichi approaches from behind and inquires how the water is, though Ichigo can only wave and mumble his praise due to his mouth being full. Acknowledging this, Yoruichi decides to have a soak as well and begins removing her pants, prompting Ichigo to spit out the water in his mouth in shock. With Ichigo spluttering over this and questioning why she is taking her pants off first, Yoruichi chuckles and reveals that she knew he would react like this, to his irritation.

After transforming back into a cat, Yoruichi enters the hot spring and notes that this form should not upset Ichigo before teasingly wondering if he is disappointed by this as an annoyed Ichigo claims he is going to drown her. Ichigo looks around the area and brings up how similar it looks to the Study Chamber underneath the Urahara Shop in the Human World, prompting Yoruichi to affirm this and reveal that Study Room was modeled on this place. While Ichigo expresses his surprise at this, Yoruichi elaborates that this was originally her and Urahara's secret playground which they built deep underneath the Sōkyoku. Though Ichigo is incredulous at the idea of secret constructing such an area, Yoruichi merely asserts that Urahara always had a talent for mischief before recalling how they played here every day as children and proceeded to train here together after he joined the Gotei 13 and she joined the Onmitsukidō.

Astonished by this, Ichigo demands to know if this means Urahara was a Shinigami and realizes that this lines up with how much he knows about Soul Society, him having a Zanpakutō, and some of the people Ichigo has met reacting strangely to the mention of his name. With Ichigo questioning what exactly he is, Yoruichi sighs and notes that she should have known Urahara would not tell him everything before deciding that there is no reason to keep it from Ichigo now that they have come this far as she informs Ichigo that Urahara was the former captain of the Twelfth Division, as well as the founder and first President of the Shinigami Research and Development Institute.

Day Two, August 6th
As dawn breaks, Yoruichi sits on the edge of Sōkyoku Hill and observes that they have two days left for Ichigo to achieve Bankai. Admitting that Ichigo has improved rapidly compared to the average Shinigami, Yoruichi mentally clarifies that this only applies to his combat skills and that his Reiryoku has not increased much at all while Ichigo finishes warming up in the Study Chamber below and looks around for Yoruichi so they can continue training. Unsure if Ichigo can truly achieve Bankai in just two more days, Yoruichi wonders if she should extend his training and recalls how they learned the delay for Rukia's execution was cut from thirty days to twenty-five.

Though this normally would have left them with only one day to save Rukia after the three days of Bankai training, Yoruichi notes their encounter with the Kōtotsu in the Dangai sent them back in time seven days when they arrived in Soul Society, giving them eight days to spare after the three days of training. Despite extending Ichigo's training being more than possible, Yoruichi remains uncertain because no one other than Urahara has achieved Bankai this way, with Urahara having developed the method and taking three days to achieve Bankai with it while believing any longer would prove dangerous. Remembering Urahara assuring her Ichigo's gifts are greater than his own are, Yoruichi admits she is not sure if Ichigo's Soul can withstand the extra days and decides to risk it if there is no change in his Reiryoku after today.

Later, Renji arrives at the base of Sōkyoku Hill and observes it is definitely Ichigo's Reiatsu he is sensing. Within the Study Chamber inside Sōkyoku Hill, Ichigo clashes fiercely with Zangetsu as he continues his Bankai training. Watching from afar, Yoruichi Shihōin questions why she feels so uneasy despite Ichigo's steady development, and as Ichigo continues to attack Zangetsu, Yoruichi describes the sensation she is experiencing as feeling like something ominous is approaching. However, Ichigo is visibly startled when the entrance at the top of the ladder leading into the Study Chamber is destroyed by an explosion of force. As he states he was wondering what Ichigo was doing down here and inquires if Zangetsu is his Zanpakutō Spirit, Renji crashes down onto the ground near Ichigo and notes Ichigo seems to be having fun training to achieve Bankai in secret before inquiring if he can join while holding his Shikai, Zabimaru, over his shoulder, surprising Ichigo with his presence.

Renji predicts that Ichigo is wondering why he is here and explains that he simply needs a place to focus on training now that there is not much time left. With Ichigo questioning what this means, Renji realizes that he should clarify this and reveals that the time of Rukia's execution has been changed once more to noon tomorrow, stunning those present. Admitting that he is not strong enough to save Rukia yet and this is why he is here, Renji walks to the other side of the Study Chamber and promises to not interfere with Ichigo's training because he already knows how to manifest his Zanpakutō Spirit before asserting that he will be training over here as Zabimaru appears next to him.

Though Yoruichi nervously claims that there is no way Ichigo can master Bankai by noon tomorrow, she is interrupted by Ichigo smashing most of the sword he is holding and declaring that she does not get to give up when this training was her idea, and when Yoruichi attempts to remind him of what will happen should he not achieve Bankai by tomorrow, Ichigo states that he does not want to hear about what happens if he cannot and proclaims that tomorrow being the target date means he will just have to achieve Bankai today while smashing the remainder of the sword against his palm, to Renji's approval. During a later break in their respective training, Ichigo explains to Renji how he wants to save Rukia because the latter saved his life and changed his fate, allowing him to become a Shinigami and protect everyone.

Day Three, August 7th
On the morning of Rukia's execution, while two members of his division are arguing and preparing to fight each other, Kenpachi makes a hard left turn into the street they are tasked with sweeping while carrying Orihime and Yachiru on his back, which leads the frightened Shinigami to frantically greet him and claim it is an honor to be sweeping the street, only for Kenpachi to ignore them as he rushes by. With Ikkaku lecturing them for not even looking like they are working, 11th Division 5th Seat Yumichika Ayasegawa threatening to kill them if he finds even one speck of dust later, and Aramaki encouraging them to do their best as they all follow, the two Shinigami are left confused by what Aramaki and the two girls are doing with Kenpachi.

Up ahead, Kenpachi asks Orihime which way they should go as he continues to run through the Seireitei, but when she attempts to direct him, Orihime is headbutted by Yachiru, who points in the opposite direction and asserts that they should go this way. With Orihime expressing pain at this and Yachiru claiming that Kenpachi thinks they should go that way as well, Ikkaku suggests that Yachiru let Orihime lead because her sense of direction is terrible, prompting Yachiru to spit on his head and tell him to shut up while making fun of his baldness. Seeing an angered Ikkaku unsheathing his Zanpakutō, Yumichika instructs him to put it away because he started the squabble while Kenpachi decides to trust his own instincts, to Yachiru's delight.

Meanwhile, within the 75th underground relief cell of the Sōgō Kyūgo Tsumesho, Uryū sees a white cabbage butterfly flutter into the room through the narrow slatted window and comments that it must be spring here, leading an embarrassed Ganju to observe that he must have cracked under the pressure of imprisonment if he is babbling about a butterfly and promises to not tell the others if Uryū decides to chase it. Snapping back to reality at this, Uryū questions why he would want to chase it and demands that Ganju address him more formally because they are not on a first-name basis, which a startled Ganju responds to by asserting he does not like Uryū either.

Uryū reiterates that Ganju should not use his first name and claims that the latter has been rude ever since they first met. With Ganju declaring that being friendly is just a Shiba Clan custom and questioning if Uryū has a problem with it, Sado instructs them to be quiet since he can hear something nearby, which Uryū and Ganju realize they can as well. Listening to several crashing sounds, Ganju notes that it is definitely getting closer, only to be surprised alongside Uryū when the noise stops altogether. Suddenly, a large hole is busted in the ceiling of the cell from above, shocking those within, and Ganju is further mortified when Kenpachi leaps down into the cell, though Uryū and Sado are merely confused by his reaction. Upon seeing Ikkaku and Yumichika standing next to him, Ganju identifies Yumichika as the narcissist with the bowl cut hairdo whom he fought prior.

Irritated by this, Yumichika inquires who Ganju is because he has a bad memory for ugly faces while holding up his Zanpakutō. As Ganju claims to have been told that he looks better with the bandages on and questions how Yumichika recognizes him, Uryū mentally observes that Ganju did not even deny that he is ugly. However, Uryū, Sado, and Ganju are all astonished when Orihime pops up from behind Kenpachi's shoulder and expresses relief that they are alright. Back in the Study Chamber, having achieved Bankai, Renji sheathes his Zanpakutō, ties up his hair, and announces that he is leaving, prompting Ichigo to state that he will see Renji later while facing away from him with another sword in his hands. Passing Yoruichi on his way to the exit, Renji asks if she believes Ichigo will be ready.

While Yoruichi tells Renji to not worry, Ichigo stands with blood and sweat pouring down his face and neck. Renji clarifies that he is not inquiring if Ichigo will be killed because the latter has come a long way, but questions if Ichigo can really achieve Bankai. However, Yoruichi merely states that no one knows, to Renji's chagrin, and closes her eyes as Zangetsu asks Ichigo if he is ready. With several clones of himself standing on the rocks and cliffs surrounding Ichigo, each wielding Zangetsu, Zangetsu warns Ichigo that he will not hold back just because time is running out, only for Ichigo to assert that he knew this and would not let Zangetsu do so if he tried.

As she watches this, Yoruichi inquires if Renji remembers the first time he stood on his own two feet, which Renji denies, and explains that he was not aware of it when he did it before questioning what made him stand up. Detailing how people know how to walk, birds know how to fly, and fish know how to stand from birth, Yoruichi attributes this to instinct and asserts that this is what makes them strive to gain power. Yoruichi concludes that Ichigo's dedication looks like instinct to her and makes her believe that he knows he can master Bankai on an instinctual level as Ichigo resumes his attack on Zangetsu. Later, a wounded Ichigo kneels before Zangetsu with a broken sword, and when Zangetsu questions if Ichigo is getting up again, the latter merely grins and asserts that he swore to save Rukia before declaring that he swore on his own soul.

Aftermath
After being broken out of their cell by Kenpachi, the Ryoka follow him and his subordinates through the Seireitei, only to find themselves at multiple dead-ends. Upon reaching a seemingly empty pavilion on top of a building connected by a bridge, Uryū nervously observes finding the right street seems to take luck as Orihime affirms ten or twenty dead-ends is not uncommon. With Yachiru irritated by this, Ikkaku points to this as proof of why he did not want her leading them, leading Yachiru to angrily bite his head. Suddenly, Yumichika senses an intense Reiatsu in front of them.

Upon being alerted of this, Kenpachi criticizes such sneaking around and demands that they show themselves as he claims that captains should not be concealing their Reiatsu. Berating Kenpachi for his arrogance and questioning if he knows what he is doing, 9th Division Captain Kaname Tōsen appears on the rooftop in front of the group alongside his lieutenant, Shūhei Hisagi, 7th Division Captain Sajin Komamura, and Lieutenant Tetsuzaemon Iba. As Tōsen inquires where Kenpachi is going with the Ryoka and if lost his honor when he was defeated, a terrified Aramaki identifies him, Komamura, Iba, and Hisagi while expressing disbelief at being confronted by four powerful opponents like this. However, though Yumichika assures Aramaki that they are outnumbered by the Ryoka's group and Aramaki asserts in turn that it is not about numbers, Kenpachi suddenly tells them to be quiet.

Kenpachi reminds Yumichika that he never said he would let the others fight before declaring that he will be fighting all four of the Shinigami at once, though he does not believe it will be enough to test his sword. In a different part of the Seireitei, Renji runs toward Senzaikyū and mentally tells Rukia Kuchiki to hold on because he is coming to save her while Byakuya watches him from a rooftop. Soon afterward, Renji finds himself confronted by Byakuya and begins battling him in order to demonstrate his new level of power. Eventually, Ichigo succeeds in achieving Bankai and makes it to the execution ceremony just in time to save Rukia, where he also demonstrates his new level of power from having trained with Zangetsu for so long against the Sōkyoku and three lieutenants of the Gotei 13.