Battle in Fugai Forest

Prologue
At the emergency meeting, Yamamoto reports that Kuna and Muguruma's reiatsu have disappeared, and the reason is unknown. The Captain-Commander says that this is the worst outcome they can imagine. Until the previous day, the matter only concerned Rukongai, but 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, Kisuke arrives at the meeting. Urahara requests to be allowed to go, but this is declined by the Captain-Commander. 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.

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. Retsu asks if it would not be better if she went to the scene to treat the wounded more quickly, but Yamamoto refuses to allow the head of medical treatment to go into an unknown situation. As a result, he has decided to send somebody else and invites Kidō Captain Tessai Tsukabishi and his lieutenant, Hachigen Ushōda to enter the room. When he asks them to head to the scene, Kyōraku remarks that it is a bad idea to send both the Kidō captain and lieutenant. When Yamamoto asks what he would suggest instead, Shunsui asks for his lieutenant to be sent. Lisa, who had been eavesdropping on the meeting, agrees to go. When Yamamoto says that Shunsui is doing as he pleases, he 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 Tsukabishi if he will step aside for her. When Tsukabishi concedes, Yamamoto finalizes the orders. As they leave, Shunsui tells Kisuke not to worry, as Hiyori is strong, though "not as strong as Lisa". As he explains, not worrying and having faith are also duties of being a captain.

Battle
In the forests of Rukongai, Hiyori evades attacks from a large shadowy figure. As the figure attacks again, Hirako arrives. He asks her why she has not drawn her sword. Hiyori replies that she could not draw it. When the moon breaks through the clouds, her attacker is revealed to be a Hollowfied Kensei. Love and Rose arrive moments later. Rose states that his mask and Reiatsu are just like a Hollow's. As Kensei roars, Hirako tells them to draw their Zanpakutō, otherwise the are as good as dead. Kensei appears behind Love and attacks him, ripping his uniform and leaving him breathing heavily. Aikawa comments that his power is what he would expect from Muguruma. Hiyori tries to stop the others from attacking Muguruma, but Hirako tells her that they have to stop him, especially if that really is Kensei. Yadomaru says that there are plenty of ways to defeat an opponent without killing them, and decides to cut his tendons. As Rose approaches Kensei, he his attacked from above by a Hollowfied Mashiro, who kicks him into the ground. Kuna then attacks Hirako, but is caught by Hachi's Kidō. Ushōda turns his attention to Muguruma and casts a Bakudō on him too. When he asks what is happening to Kensei and Mashiro, Muguruma breaks out of the Kidō, stunning Hachigen.

Outside a Twelfth Division building, a dark, cloaked figure walks. Tsukabishi tells the figure that making a cloak that completely blocks one's Reiatsu is not an everyday achievement. Urahara reveals his face underneath the cloak, and Tessai asks him if he is planning on rescuing Hiyori. Tessai tells Kisuke that he thought this would happen when he saw Kisuke at the meeting earlier. Tessai reminds him that they spent a lot of time together at Yoruichi Shihōin's mansion, so he would not have failed to notice such things. When Kisuke asks if he can pass, Tessai says that he will not allow him to go alone. He says he is sensing an unfathomable terror and that they shall go together. As Kyōraku walks around the Seireitei in the darkness, he comes across two guards, who ask if everything is alright. Shunsui tells them that he was just having trouble sleeping. He spots Aizen and comments that perhaps he was over-thinking it. When one of the guards asks what he means, he dismisses it as nothing and says 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 they say good night to each other. When he returns to the Eighth Division barracks, Shunsui comes across Nanao Ise, holding a book. Shunsui remembers her name, and she tells him she is honored because by this. He tells her that he always tries to make note of the young girls' names, and Nanao visits him every month. Nanao says she wanted to read with Lieutenant Yadōmaru again, but Shunsui informs her that Lisa is not there. When she asks why, he says that she is on an important mission, but will be back by dawn.

In Rukongai, Yadōmaru is injured by Kensei. Rose attacks him, saying that Kensei was not the type of person to attack a woman. Hachigen uses Bakudō #99 Kin to restrain Muguruma, commenting that he may have overexerted himself. Hirako asks him if he can do something about their condition with Kidō, but Ushōda states that without knowing the cause, there is little he can do. When Hiyori starts coughing again, Hirako tells Hachi to heal all of them, starting with her. Hiyori tells Shinji to let her go as fluid flows from her mouth. Hirako is cut across the chest as a Hollow mask forms on her face. 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. Aizen appears and tells his captain that Tōsen has not betrayed anyone and that he has followed his orders. Sōsuke 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 continues to explain to the shocked Shinji that if he had engaged with him as any other captain would with their lieutenant, he might have been able to see through it. However, as Shinji did not trust him, he get his distance and did not give him 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 reminding Hirako that a Shinigami has the right to refuse promotion and he did not refuse because Hirako's distrust was ideally suited for his goals. Aizen tells his captain that he should apologize to his allies, as it is because Aizen chose him that they are all lying on the ground, infuriating 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 excited stated. When Hiyori sees this, she calls for Hirako, but at Aizen's command, she is cut down by Tōsen.

Aftermath
Aizen draws his sword to kill Hirako, calling them all wonderful test subjects, but is attacked by Urahara, who is wearing his Reiatsu blocking cloak. Kisuke cuts off Aizen's lieutenant insignia.