The Hollowfication Incident

 is a major incident detailing the history of the Visored's creation and the ascendancy and fall of Kisuke Urahara within the Gotei 13. It further goes into the onset of the first attempts of Hollowfication by Sōsuke Aizen over one hundred years ago.

The incident started with the appointment of Kisuke Urahara as captain of the 12th Division after the promotion of Kirio Hikifune to the Royal Guard. Using his new status, he creates the Shinigami Research and Development Institute in order to put his inventions to good use.

Nine years later, Aizen conducts Hollowfication experiments on residents within the Rukongai prompting an investigation from the Gotei 13. The 9th Division are tasked with the mission, but most of its highly ranked officers are cut down and the captain and lieutenant are Hollowfied. This prompts further investigation and the team that are sent out are also subjected to the experiments. The arrival of Urahara saves them from slaughter, but Aizen escapes. When he fails to save them, Urahara is arrested and charged with the crimes. With the help of Yoruichi Shihōin he and the Visored escape to the Human World.

Prelude
One hundred and ten years ago, Shinji Hirako and Sōsuke Aizen, captain and lieutenant of the Fifth Division respectively go to the First Division barracks to attend an inauguration ceremony. When the door opens, Hiyori Sarugaki greets Shinji by kicking him in the face causing a fight that Love Aikawa interrupts by thumping her on the head.

Love pushes an angry Hiyori back into the barracks and they all walk through the building discussing those who are attending, including the fact that Kenpachi Kiganjō is lazy and disobedient. Shunsui Kyōraku interrupts them along with Jūshirō Ukitake. They discuss the constant changing of captains over the years with himself, Ukitake and Genryūsai Shigekuni Yamamoto being the longest serving. Ukitake has to remind him of Retsu Unohana.

During the discussion, Kyōraku reveals that Kirio Hikifune has been promoted to Aizen and the other lieutenants present. Curious, Aizen question Kyōraku on how this is possible and whether it was to Central 46. Thus, Kyōraku informs them of the existence of the Royal Guard, otherwise known as the Zero Division. The information greatly stuns Aizen speechless.

Kensei Muguruma interrupts their conversation, informing everyone to get in line and they do so just before Kisuke Urahara then arrives in the room. Urahara apologizes, but is chastised by Yoruichi Shihōin for not behaving like a captain. Yamamoto arrives by pushing him into the room before formally announcing that Urahara has completed the Captain Proficiency Test and as such is the new Captain of the Twelfth Division.

Urahara receives a cool reception from his new subordinates, but his new lieutenant, Hiyori, takes a strong disliking to him. She tries to get a rise of out him by insulting his former position as a member of the Second Division, but Urahara does not rise to the bait stating that his loyalty now lies with his new division. This infuriates Hiyori, who kicks him before storming off.

Later that night, Urahara sits at the railings outside his barracks and is approached by Shinji who accurately predicts that Urahara is having trouble with Hiyori. He explains that Hiyori is having trouble over losing Hikifune as her captain as they were close. When Urahara assumes he will never be good enough for her, Shinji lets him know that captains can never please their subordinates all the time, but even then, they should still do what they feel is right for each of their divisions. As Shinji leaves, he uses Noren Mekuri to reveal Aizen who had been spying on the conversation and they both state that the other is intimidating.

Early Stages
Hiyori continues to struggle to accept her new captain, Urahara, although much of her subordinates are welcoming and helpful in his changes. She discovers that he has totally remodeled his new office, installing a lot of different technology. She perceives this as him eliminating all reminders of Hikifune's tenure there and this infuriates her. She demands to know why he is changing Hikifune's things, but he reminds her that the office is now his to change as he prefers. She punches him for this, but he ignores the transgression and informs her that he is making new changes and wants her to come to the Nest of Maggots with him.

Urahara brings a reluctant Hiyori to the Nest of Maggots giving her a history regarding the Onmitsukidō and how he was head of the Detention Unit. He reveals that he guarded the Nest of Maggots and was required to have superior Hakuda abilities as weapons wee not allowed. He reveals that anyone whom she knew has withdrew from the Gotei 13 was really detained by Central 46 as they were considered dangerous. A detainee suddenly attacks Hiyori who panics without her Zanpakutō. Urahara intercepts the blow and apologizes for not warning her. He easily defeats the attacker.

They soon come upon an isolated prisoner, Mayuri Kurotsuchi. Urahara reveals his plans to establish the Research and Development Institute and he wants Mayuri as its Vice-President and thus will inherit the organization if Urahara dies. After initially rejecting the possibility of working with Urahara, this revelation intrigues Mayuri, who smiles and states that Urahara is an unpleasant man.

Meanwhile, Byakuya Kuchiki is training when his grandfather brings Yoruichi to visit him. She teases him several times, inciting his anger, before stealing the tie for his hair. She taunts his ability to catch her and he responds by chasing her using Shunpo leaving Ginrei Kuchiki wondering about his youthful temper. Elsewhere, Ukitake visits Kaien Shiba to try and entice him into becoming his lieutenant, but the Shinigami declines the offer, depressing him. They discuss a new Gotei 13 recruit who graduated from the Shin'ō Academy in a year before joining the Fifth Division as a seated officer.

At the Fifth Division barracks a fight has just concluded in the meantime. The newest member of the division, the Shinigami who graduated inside a year, has defeated the 3rd-Seat in a battle and killed him while doing so. An observer, Aizen, walks forward and asks the young Shinigami his name and he replies that it is Gin Ichimaru. Aizen compliments his talent and asks how he found the abilities of his opponent. Smiling in a mocking fashion, Gin insists that his opponent was hopeless, not worth mentioning in the future. Aizen calmly replies that the knowledge is good to know.

Middle Stages
Nine years after Urahara's promotion, disappearances and strange deaths begin occurring in the Rukongai with three unknown suspects carrying out experiments. Followed by Aizen, Shinji meets Urahara and his subordinates while out for a stroll in the Seireitei. After a scuffled with Hiyori, he informs Urahara about the disappearances of souls in the Rukongai. He insists that they are just losing their Human form and leaving behind their clothes, at least this is Unohana's theory. This concept confuses Urahara, but he wonders if he can do or make something that can provide a human form for those disappearing to prevent it from happening. Shinji asserts that he does not understand what is happening, but the investigation has been assigned to the Ninth Division.

Kensei takes a small group of his high ranking officers to investigate in disappearances. His lieutenant, Mashiro Kuna, follows them and complains incessantly about their mission, maintaining several times that a captain should not be on such a mundane mission. Kensei reveals that he had previously sent out ten lower ranked Shinigami to investigate, but they have been late in reporting in and this is the reason for him assembling a smaller, higher ranked group of Shinigami for the task. Mashiro begins to have a temper tantrum over the issue and Kensei has to be held back from hitting her.

They are interrupted by three young souls being chased by a massive Hollow. Kensei immediately orders his men to attack the beast and they speedily obey his orders. They each deliver many slices to the Hollow, but it still stands and knocks one of the young souls to the ground. The child looks up and sees Kensei standing over him, ready to engage the beast. The captain releases his Zanpakutō Tachikaze and promptly eliminates the Hollow before checking to see if his men are unhurt. Kensei approaches the child, who sobs in panic and reveals his name to be Shūhei Hisagi. Kensei tries to get him to stop crying, but his efforts only serve to increase his despair.

Mashiro reveals that she has found ten sets of shihakushō in a nearby bush. Kensei realizes that they belong to the Shinigami unit he has previously sent out to investigate the area. He insists that they have become victims too as their socks are still inside their sandals. He orders his officers to report to Central Command that the incident has claimed Shinigami victims. He sends Izaemon Tōdō to the S.R.D.I. in case there is an unseen pathogen. He tells the children to go home as it isn't safe. Hisagi spots Kensei's tattoo of the numbers 69 and it makes an impression on him.

At the S.D.R.I., Mayuri and Hiyori get into an argument about which of them has seniority over the other before Hiyori yells to wake Urahara up. He enters the room with a body over his shoulder which he explains is a Gigai he is trying to invent to help the disappearance victims. Tōdō arrives and reports what has happened to the ten Shinigami. Urahara politely dismisses him and tell Hiyori that he wants her to go. She stubbornly refuses to, but Urahara reveals that the samples will be important and he needs to send a researcher he can trust so she reluctantly agrees to go.

Tōdō returns to the site where a camp has been set up and others are standing guard where they decide to take turns. Inside the tent, Mashiro is sleeping soundly which aggravates Kensei, even more so when she rolls over and almost exposes herself. Cries from outside alarm him and he heads out to investigate. He finds his officers mostly slain before he sees Tōdō and he too collapses to the ground. Kensei tries to wake Mashiro, but Heizō Kasaki is cut down as well. In the confusion, a darkness suddenly surrounds the area and Kensei is stabbed from behind through the abdomen.

Yamamoto assembles an emergency meeting and informs the captains of the disappearances of the Reiatsu of both Kensei and Mashiro declaring that they must assume the worst. He decides to send 5 captains to the area. Urahara arrives and asks to be on the team, but Yamamoto denies the request and when Urahara tries to argue, he is berated by Yoruichi. Instead, Yamamoto chooses Love, Shinji and Rose to go to the site while Yoruichi is to wait on standby. Unohana requests to go, but Yamamoto denies her request as well as he needs to make sure his healers are safe from the cause until they know what it is.

Tessai Tsukabishi, captain of the Kidō Corps and his lieutenant, Hachigen Ushōda, arrive to the meeting. The others are shocked as Tessai is usually a recluse. Seeing Urahara, Kyōraku suggests sending his lieutenant, Lisa Yadōmaru, instead of sending two high ranking members of the Kidō Corps. She reveals herself to be eavesdropping and agrees to go. While the others are leaving, Kyōraku approaches Urahara and tries to reassure him about Hiyori being able to look after herself. He asserts that waiting for their subordinates to complete missions is also part of a captains duty. Urahara watches him sadly as he leaves.

In the forest, Hiyori is being attacked and trying to evade the blows. Shinji arrives and manages to parry an attack that likely would have connected. The reason Hiyori did not draw her blade becomes obvious when the attacker is revealed to be a Hollowfied Kensei. The others arrive and are equally stunned by the sight of Kensei. They draw their blades and evade an attack, but Kensei appears behind Love and hits him to the ground, injured, but still standing. Hiyori tries to get them to stop, but they reassure her by insisting there is more than one way to stop him without killing him.

As Rose and Lisa move in to attack Kensei, Rose is ambushed by Mashiro, who is also Hollowfied, when she kicks him on the head. She goes on to attack Shinji, who is holding Hiyori, but Hachi arrives and uses Kidō, '''Bakudō # 75. Gochūtekkan''', to knock and imprison Mashiro to the ground. After catching his breath, he uses Bakudō #63 Sajō Sabaku on Kensei, tying him up with chains. However, in his new state, Kensei manages to break free of the high level Kidō with brute force alone, causing the others to marvel at his strength.

Elsewhere, Tessai confronts Urahara about trying to sneak to the investigation site wearing a cloak that blocks his Reiatsu completely. He reveals that they grew up together and knew he would try and help so Tessai agrees to go to the site with him due to his fear over what is happening. In the Seireitei, Kyōraku investigates the Fifth Division barracks only to see Aizen carrying books and greeting him. He leaves the site wondering if he had misjudged the situation. In his own barracks he comes across a young Nanao Ise, who asks where Lisa is and he reveals she is on an important mission and should be back soon.

At the battle, Lisa and the others are faring badly with many injuries. She is knocked to the ground and Rose tries to distract Kensei from attacking her by insulting him. Hachi manages to use '''Bakudō #99. Kin''' to bind Kensei to the ground, much to the praise of Shinji. While they discuss whether they can cure Kensei and Mashiro, Hiyori begins to cough and convulse in Shinji's arms as she tells him to drop her. Suddenly, she slashes Shinji with her blade and knocks him to the ground. She lets out a Hollowfied cry as a mask forms on her face.

Before the others can act, a darkness envelopes the area and those remaining are cut down. The assailant is revealed to be Kaname Tōsen of the Ninth Division and a still conscious Shinji asks how he can betray his superior. Aizen and Gin arrive on the scene and reveal that Tōsen has in fact been very loyal to his true master. Shinji reveals that he has always been suspicious of Aizen, but his lieutenant asserts that his suspicion was the very reason he was able to fool him. He states that the man following him for the last month has not been Aizen, but someone he taught his mannerisms too which is the true power of 'Kyōka Suigetsu, complete hypnosis.

Aizen taunts Shinji, asserting he choose to be his lieutenant and not the other way around. Shinji becomes enraged and draws his blade to attack, but is suddenly taken over by the same convulsions that affected Hiyori as a white substance explodes from his face as he realizes he has been infected. Unfazed, Aizen thanks Shinji for getting angry as it was able to show him that anger speeds up the process. The others begin to Hollowfy too. Shinji asks what Hollowfication is, but Aizen draws his blade and asserts he doesn't need to know. Hiyori manages to call out Shinji's name, but Tōsen cuts her down with Aizen's prompt.

Aizen thanks Shinji for his attitude towards him and lifts his blade to attack his captain. However, from behind, Urahara arrives and slashes off his armband before he can do so. Gin remarks that they have been found and Tōsen goes to kill them, but Aizen denies his request. Urahara asks what is going on after seeing the others including Hiyori. Aizen lies and says he is trying to help them, but Urahara asks why he is lying. He also reveals that he knows that the injuries are from Hollowfication and not mere slashes from a blade impressing Aizen.

Aizen sheathes his blade and states that he is glad Urahara showed up tonight before turning away from the scene, telling his subordinates to follow him. Urahara moves to get them to wait, but Tessai demands that he get down before using Hadō #88 Hiryū Gekizoku Shinten Raihō to attack the retreating trio. Aizen blocks the Kidō with a chantless Bakudō #81 Dankū which greatly surprises the Kidō Corps captain due to Aizen merely being a lieutenant. When the dust clears the trio has vanished and Tessai apologizes to Urahara for letting them get away.

Ending Stages
In order to save time so that Urahara can try and help the victims, Tessai uses two forbidden Kidō spells to move them to Urahara's lab. Urahara quickly gets to work in his lab, revealing the existence of his Hōgyoku to Tessai and reveals that it breaks down the barriers between Shinigami and Hollow. He tries to use the Hōgyoku to save the captains and lieutenants affected by Aizen's Hollowfication experiment. He works all night towards this end, but he collapses with exhaustion and announces his failure in the task.

Urahara heads outside for fresh air where he is suddenly surrounded and both he and Tessai are taken into custody. They are brought to a tribunal held before Central 46 where they are accused of conducting the Hollowfication experiments that were carried out by Aizen. Urahara tries to protest their innocence, but the fact that Aizen was seen by Kyōraku allows his defense to be dismissed. They sentence Tessai to imprisonment in the Underground Prison 3, 'Shugō' for using forbidden Kidō techniques. Urahara is sentenced to being stripped of his powers and banished to earth. Shinji and the other victims are sentenced to be dealt with like Hollows.

They are interrupted by the arrival of a masked individual who smashes their shackles and takes them all to the Secret training ground underneath the Sōkyoku Hill where they have taken the victims of the infection as well. It is revealed to be Yoruichi and Urahara thanks her. She berates them for not coming to her for help. She reveals that she brought his prototype Gigai that he was working on and Urahara decides to work on Gigai for himself, Tessai and the infected so they can hide in the Human World until he finds a cure and he swears that he will find a way to reverse the Hollowfication.

Today, the Visored are sitting in their warehouse reminiscing on how they gained their powers over a hundred years ago. Shinji reminds them that Urahara had made that promise, but he discovered that the biggest miscalculation he had made was that there were no miscalculations. Thus, the worst possible outcome happened. Standing up, Shinji asserts that they are indebted to Urahara for all he has done. However, he claims that they are also indebted to Aizen. The rest of the Visored stand up and walk out towards battle.