Battle in Fugai Forest

Prelude
After the disappearances in Soul Society begin and the 9th Division Task Force that is led by Lieutenant Kuna and Captain Muguruma disappear in their investigation of the incident, Captain-Commander Yamamoto calls for an emergency meeting of the Gotei 13.

At the emergency meeting, Yamamoto reports that Kuna and Muguruma's Reiatsu have disappeared, and the reason is unknown. The Captain-Commander says that they must assume the worst until they know more on the situation. Until the previous day, the matter only concerned Rukongai, but Yamamoto declares it is now an issue which must be resolved on the pride of the Gotei 13. As Yamamoto says that he will send five captain-class Shinigami to the scene, Urahara makes a late arrival at the meeting.

Urahara immediately requests to be allowed to go, but the Captain-Commander declines his request. Kisuke tries to argue with him, but is stopped by Yoruichi, who tells him not to lose his composure. She states that since he chose Hiyori to go on the mission, his actions are an insult to her.

Because of this crisis, Yamamoto selects Captains Hirako, Rōjūrō Ōtoribashi, and Love Aikawa to go to Rukongai, while Yoruichi is to stand-by for separate orders. Captains Ginrei Kuchiki, Kyōraku, and Ukitake are told to guard Seireitei. Captain Unohana is told to prepare her medical facilities for incoming casualties. Unohana asks if it would not be better if she went to the scene to treat the wounded, but Yamamoto refuses to allow healers to go into an unknown situation.

As a result, he has decided to send others and invites the Kidō Corps Captain Tessai Tsukabishi and his lieutenant, Hachigen Ushōda to enter the room. Both Kyōraku and Ukitake are surprised to see the Kidō Corps’ top officers after a long time of not seeing them. Yamamoto notes that he assumes the two are aware of the current situation and asks them to head to the scene, to which both Shinigami accept the order.

As this occurs, Kyōraku notices Urahara’s worried look. He then remarks to Yamamoto that it is a bad idea to send both the captain and lieutenant of the Kidō Corps into an unknown situation. Yamamoto asks what he would suggest instead. In response, Kyōraku asks for his lieutenant to be sent. He then calls for Lisa, who had been eavesdropping on the meeting. As Kyōraku briefly scolds Lisa for eavesdropping, he checks with Lisa if she is willing to go the scene. Lisa agrees. Yamamoto notes how Kyōraku is doing as he pleases, to which Kyōraku replies that it is rare for such an event to occur, and he would like to give her some experience. He comments that Lisa is strong, and asks Tessai if he will step aside for her. Tessai concedes and Yamamoto finalizes the orders.

The meeting ends and the captains all begin to leave the hall as Urahara stands there stunned and worried. Kyōraku notices this, pausing at his side and placing a sympathetic hand upon Urahara's shoulder. He tells his fellow captain not to worry about the situation as Hiyori is a strong Shinigami but still not as strong as his Lieutenant, Lisa. He advises Urahara that waiting and having faith in their subordinates is also part of a captains duty. Kyōraku then leaves as a silent Urahara watches him go, his expression being one of worry and concern.

Battle
In Fugai Forest, outside the Seireitei, Hiyori is fleeing from an assailant, panting heavily as she does so. She is also injured with a number of wounds on her face. She is forced to evade attacks from a large shadowy, one of which causes a massive disturbance in the ground. Having dodged the attack, she stares at the massive figure, wiping blood from her face a swearing about her predicament. Her assailant moves in for another attack while Hiyori does not move to evade it.

As the attack is about to land, Shinji arrives on the scene and uses his Zanpakutō blade to block and parry the blow. Hiyori is stunned by his arrival, barely able to mutter his name. Shinji angrily chastises her and demands to know why she has not drawn her own blade. Hiyori insults him for this, her facial expression becoming downcast as she insists that she could not draw her blade against her assailant. The cloud moves away from the moon then and the added light reveals that her assailant is, in fact, Kensei and he's become a massive Hollowfied figure. Upon recognizing his fellow captain, this revelation greatly shocks Shinji.

While Shinji stands stunned, the others of the advanced team arrive on the scene. Love asks Hiyori if she is hurt before they too spy the tattoo on the Hollow's chest and realize that Kensei has become Hollowfied. Love demands to know what is going on while Rose wonders if the beast can really be Kensei consider the mask and other mutations that cover his body; he compares his appearance to a Hollow. Shinji agrees with them, not knowing whether or not the creature really is Kensei, but he implores his comrades asserting that if they do not draw their weapons, they will likely die.

Kensei lets out a loud Hollow cry along with a blast of Reiatsu, causing the group to split up to avoid him. Despite this, Kensei manages to get behind Love and catch him off guard. Before Love can do anything, Kensei punches him to the ground. The others yell out to him, concerned, but the captain remains standing with his blade drawn but is injured as a result, commenting that he wouldn't expect anything less from someone like Kensei. In the crook of Shinji's arm, Hiyori yells for them not to attack Kensei considering he is their fellow comrade.

Before she can finish what she is saying, Hiyori is overcome by a fit of coughing and convulsions. Concentrating on the situation at hand, Shinji advises her to remain quiet. As she regains control, Shinji insists that if the Hollow really is Kensei then that makes defeating him an even bigger priority than if he was a normal Hollow. Rose reinforces Shinji's opinion stating that Kensei is very strong, and thus they must stop him for that reason. Lisa draws her Zanpakutō while encouraging Hiyori not to worry about Kensei's safety given that there are many ways to stop him without having to kill him. Beside her, Rose also draws his blade.

Lisa informs Rose that she plans to cut Kensei's muscle tendons in order to disable his movement. She tells Rose to take his right side while she takes his left and the captain agrees. The two of them move in to attack the Hollow but their concentration on Kensei allows Mashiro, who has also been Hollowfied, to appear behind Rose and ambush him. Lisa notices her at the last moment and tries to warn the fair-haired captain but Mashiro manages to land a devastating kick on the top of his head, sending him crashing into the ground. The impact causes massive amounts of damage to the area and Rose lies injured among the debris as Lisa calls out to him.

Shinji is stunned to see that Mashiro has also gone through the same type of transformation that has affected Kensei. When he calls out her name, she notices him and immediately moves in to attack both he and Hiyori. Shinji is able to block her kick with his blade, causing an explosion around them as he struggles against her power. Hacchi suddenly arrives on the scene and surprises the Hollowfied Mashiro by using Bakudō #75 Gochūtekkan. He catches he off guard as the incredibly large pillars fall from the air and pin her to the ground.

Hacchi takes a moment to catch his breath and he complains, while panting heavily, that the entire advance team of Shinigami ran very quickly to the area and left him behind. While Shinji expresses his surprise at the arrival of their large comrade, Hacchi looks up and notices Love fighting against Kensei in the air. He raises his hand and closes his fist to use Bakudō #63 Sajō Sabaku, summoning thick yellow ropes that surround and then bind the upper body of the Hollowfied captain. Disabling him, the binds cause him to fall to the ground.

With the threat disabled, Hacchi calls out to Shinji and demands to know what is going on. He wants to know what Kensei and Mashiro have been transformed into Hollow-like beings. However, before he can finish his inquiries he is interrupted by an increase of Reiatsu coming from Kensei as he moans on the ground. Hacchi looks down and notices that the large ropes, that are binding the infected captain, are breaking apart. Hacchi is stunned to see the captain break free of the spell as he has never heard of anybody breaking out of a Level 60 binding spell using brute strength alone.

Outside the Twelfth Division barracks, a cloaked figure walks by in the dark. The individual is confronted by Tessai who comments that the cloak is an interesting new invention he hasn't seen yet as it completely blocks one's Reiatsu ans is, thus, quite extraordinary. Urahara reveals himself, smiling sheepishly, underneath the cloak, and Tessai asks him if he is planning on rescuing Hiyori. He advises Urahara that he thought this would happen when he saw Urahara at the meeting earlier and the inventor does not deny his intentions, realizing he should have known Tessai would guess his plan.

Tessai reminds Urahara that they spent a lot of time together at Yoruichi Shihōin's mansion whilst growing up, so he would not have failed to notice such things. Urahara wonders aloud whether or not Tessai is going to allow him to pass without incident but Tessai reveals that he does not intend on preventing him from helping his lieutenant. In actuality, Tessai seriously states that he cannot allow Urahara to go investigate the issue alone as he has been filled with an intense fear all evening. He beckons Urahara to hurry so they can get to the scene before any more horrors occur.

While this occurs, Kyōraku is walking around the Seireitei in the darkness keeping and eye out. He comes across two guards at the Fifth Division barracks and compliments them for keeping vigilant. Curious, they ask him if everything is alright but the Eighth Division Captain insists that nothing is wrong and that he is out because he couldn't sleep. Kyōraku spies Aizen carrying a pile of books back to his rooms and wonders if he was over-thinking matters. The guards question his meaning but he dismisses it as nothing, saying that Aizen seems to be having similar trouble sleeping. As the guards say good night to Aizen, Kyōraku tells them to get some rest and leaves.

After the guards bid him goodnight, Kyōraku returns to the Eighth Division barracks to find a small recruit standing in the yard alone holding a book. After some thought, Kyōraku asks if her name is Nanao Ise and the young Shinigami nervously confirms that she is honored he remember her name. Kyōraku asserts that it was easy given she's the youngest member of his squad and he always remembers the names of young ladies. Nanao asserts that she has come to read with her lieutenant but Kyōraku apologizes, revealing that Lisa is out on an important mission. He reassures her by maintaining he was sure she would return in the morning.

In Rukongai, Yadōmaru is injured by Kensei and she is sent falling into the ground. Kensei moves in to attack again, but Rose attacks Kensei. He implores Kensei to stop, stating that he was not the type of person to attack a woman. The Hollowfied-Kensei simply roars and goes after Rose instead. Hachigen then uses Bakudō #99 Kin to restrain Muguruma. Hirako compliments Hachigen on his skills, to which Hachigen comments that he may have overexerted himself as he breathes heavily. Everyone then goes to examine Kensei. Hirako asks Hachigen if he can do something about their condition with Kidō, but Ushōda states that there is little he can do without knowing the cause. Hiyori then starts coughing again, with Hirako wondering if she is alright. He tells Hachi to heal all of them, starting with her. Hiyori tells Shinji to let her go as fluid flows from her mouth. All are surprised to see Hirako be cut across the chest as a Hollow mask forms on Hiyori. As Lisa and Love rush towards her, they are shrouded in darkness. Heading noises in the dark, Love calls out to his fellow Shinigami, but is cut down. As the light returns, Hirako recognizes Kaname Tōsen and asks him why he betrayed his captain Sōsuke Aizen appears with Gin and answers his captain’s question appears, telling Hirako that Tōsen has not betrayed anyone as he has followed his orders. Aizen asks Shinji not to blame Kaname for what he has done.

Upon realizing that Aizen is responsible for what has happened, Hirako reveals that he has suspected him since before he became his lieutenant. Hirako tells Aizen that he chose him as his lieutenant so that he could keep an eye on him, as he viewed Aizen as dangerous and untrustworthy. Aizen thanks Hirako for this, saying that it was thanks to those misgivings that he failed to notice that for the previous month, Aizen had substituted another Shinigami for himself. Aizen tells Hirako the ability of his Zanpakutō, Kyōka Suigetsu, can cause anybody to misconstrue what they see. He calls this ability “complete hypnosis.” He continues to explain to the shocked Hirako that he might have been able to see through it if he had engaged with him as the other captains did with their lieutenants. However, Hirako did not trust him, kept his distance and did not share any information. Due to this, he did not notice when Aizen switched places with another person, who had memorized his normal behavior and responses to other members of the division and the other captains. Aizen finishes his explanation by saying Hirako’s intention to keep an eye on him by making his lieutenant is wrong and reminding Hirako that a Shinigami has the right to refuse promotion. Despite how rare this is, it is something that he could have done. Aizen tells him that he did not refuse because Hirako's distrust was ideally suited for his goals. Aizen tells his captain that it is not Hirako who chose him, but rather him choosing Hirako. He adds that Hirako should apologize to his allies, as it is because Aizen chose him that they are all laying on the ground. This infuriates Hirako. As he gets up to attack Aizen, fluid erupts from his mouth and eye, forming into a Hollow mask. Aizen thanks Shinji for rising to his taunt, as it confirms his suspicion that the Hollowfication occurs more quickly when the subject is in an agitated state. Hirako wonders what Aizen is talking about, but Aizen simply remarks that he does not need to know. Hirako then begins screaming as his Hollowfication takes place. When Hiyori sees this, she calls to Hirako. Aizens sees this and has her cut down by Kaname. As Hirako stares in disbelief, Aizen tells him that it is time to end things. Aizen again remarks on how perfect Hirako was for Aizen’s plans with his vigilance and distrust. He draws his blade to kill Hirako and bids farewell, noting that “the betrayal you can see is trivial. What is truly fearsome, is the betrayal that you don't see.”

Aftermath
With his blade drawn, Aizen prepares to kill Hirako and calls them all wonderful test subjects. Hirako curses, causing his Hollowfication to advance. However, Aizen is then stopped by Urahara in his Reiatsu blocking cloak. Urahara cuts off Aizen's division insignia armband. As Aizen, Kaname and Gin notice the arrival of Urahara and Tessai, Aizen remarks that they have yet another interesting guest. Urahara and Tessai then confront Aizen, Kaname, and Gin on what they were doing. They also attempt to save the Hollowfied Shinigami.