Zanpakutō Rebellion

The  is an event in which Muramasa, a Zanpakutō spirit, frees many other Zanpakutō Spirits from their masters and starts a rebellion under the guise of wanting to free all Zanpakutō Spirits from the control of Shinigami. In truth, he sought nothing more than to free his master, Kōga Kuchiki, who was sealed away long ago.

The rebellion began when Muramasa appeared and began freeing the many Zanpakutō Spirits. The Shinigami begin to lose the ability to contact their Zanpakutō Spirits. Muramasa leads the spirits to a confrontation with the Shinigami atop Sōkyoku Hill. The Shinigami, now unable to use their Zanpakutō, are unable to deal with their former Zanpakutō, throwing the Seireitei into a state of emergency.

The event ended after Ichigo Kurosaki entered the dome-like structure that an out-of-control Muramasa created. Ichigo fought Muramasa and, after a fierce battle, managed to defeat the Zanpakutō Spirit, ending the rebellion and Muramasa's control over all Zanpakutō Spirits that had not already been freed.

Prelude
After many Shinigami receive Jigokuchō telling them to go to Sōkyoku Hill, Lieutenant Chōjirō Sasakibe approaches all those gathered, but soon falls unconscious. A mysterious man approaches them and Captain Sajin Komamura activates his Bankai, but is cut down by his own Zanpakutō Spirit. Members of the Gotei 13 attempt to release their Zanpakutō, but are unable to. The leader says he has freed the Zanpakutō Spirits from Shinigami control. Several other Zanpakutō appear and attack the Gotei 13 members. Muramasa, the leader denounces the Shinigami. The Shinigami find themselves outclassed, but Captain Byakuya Kuchiki tries to subdue Muramasa. Muramasa commends him, but summons Byakuya's Zanpakutō Spirit, Senbonzakura.

Confronted by his own Zanpakutō, Byakuya goes on the defensive, using Shunpo to get away from Senbonzakura. Byakuya runs across the rooftops before seemingly being swallowed by Senbonzakura's Bankai as he jumps. Meanwhile, after being pursued by her Zanpakutō, Sode no Shirayuki, Rukia Kuchiki manages to open a Senkaimon to the Human World and falls to the ground, injured before being caught by Ichigo. Sode no Shirayuki arrives and attacks Ichigo. Confused, he asks how she is able to use Rukia's attacks, but the Zanpakutō Spirit continues to attack Ichigo. Ichigo gains the upper hand before Sode no Shirayuki creates a diversion to escape. Ichigo then takes Rukia back to recover and she reveals to Ichigo and everyone what happened in Soul Society.

Later, Rukia disappears and Kisuke Urahara mentions that she has likely returned to Soul Society. Ichigo and Yoruichi Shihōin decide go to Soul Society to help. Rukia meanwhile rushes trough the Sixth Division barracks in search of Byakuya. She runs into her Zanpakutō Spirit and tells her to stop attacking innocent people, but Sode no Shirayuki says she no longer takes orders from Rukia. Initially stunned to see Sode no Shirayuki using her attacks, Rukia eventually realizes why Sode no Shirayuki left her and decides to finish the battle by binding herself to her Zanpakutō Spirit and firing a '''Hadō. 73''' at her, trying to kill herself along with Sode no Shirayuki, in order to "set her free".

In the crater left by Rukia's attack, Muramasa arrives to retrieve Sode no Shirayuki. Muramasa reveals himself as a Zanpakutō Spirit and explains that he will release all Zanpakutō from Shinigami control. Ichigo proposes a change of location and they take off before Muramasa gets the better of Ichigo and releases Zangetsu. Zangetsu attacks Ichigo and as the smoke clears, and Ichigo walks out with mask half on and chases Zangetsu to a new location. Zangetsu attacks and when the smoke clears, Ichigo's inner Hollow has taken full control of Ichigo's body. Ichigo's inner Hollow goes into a berserk rage, but soon Ichigo regains control and rips his mask off. His body returns to normal and he falls, only to awaken in his inner world with Muramasa in there. Muramasa pulls Hollow Ichigo out and Muramasa fights him, eventually trapping him in his invisible wires before Ichigo frees him and returns to Soul Society. Gaining a new resolve, Ichigo's inner Hollow loans Ichigo his power and he uses a powerful Getsuga to finish the battle. Muramasa suddenly grows weak and fades away. Zangetsu is freed from Muramasa's control and explains how dangerous Muramasa and that he must be stopped.

Meanwhile, Lieutenant Renji Abarai is confronted by Zabimaru whom he does not recognize at first. Only once Zabimaru summons their Shikai does he realize it is his Zanpakutō. Renji is forced to find his reason to fight and gains a new resolve, allowing him to summon his Shikai and eventually defeat his Zanpakutō Spirit by using Higa Zekkō. Elsewhere, Lieutenant Shūhei Hisagi runs into Kazeshini, who has been cutting down everyone he runs across. Hisagi confronts Kazeshini in a forest and resolves to kill him, not caring if he can no longer use his Zanpakutō. Kazeshini eventually knocks Hisagi to the ground and wounds him before he goes to deal the final blow, but he is stopped by Lieutenant Izuru Kira.

Early Stages
Later that night, Lieutenant Marechiyo Ōmaeda walks with his subordinates to find records of if a Zanpakutō called Muramasa ever existed. As he does, he comes across the fallen bodies of many Shinigami and is then confronted by a Zanpakutō Spirit who he quickly recognizes as his own Zanpakutō, Gegetsubri. Marechiyo gets knocked out as Ichigo and Third Seat Ikkaku Madarame arrive. Ichigo makes quick work of Gegetsubri and Ikkaku face his own Hōzukimaru. The two engage in Ikkaku's lucky dance before Hōzukimaru uses his Bankai. Before the fight can conclude though, Captain Suì-Fēng arrives to apprehend the Zanpakutō Spirit, but Hōzukimaru escapes and Ichigo chases after him before encountering a figure up ahead, Byakuya.

As Ichigo runs after Byakuya, he is confronted by Tobiume and Haineko, but easily escapes while the two bicker. The two spirits are then confronted by their owners; Lieutenants Momo Hinamori and Rangiku Matsumoto. Initially each take on their own Zanpakutō, which does not work out well for the two Shinigami. However, the two lieutenants manage to trick the Zanpakutō Spirits by switching opponents and promptly defeating the two, tying them up and celebrating afterward. Elsewhere, Captain Tōshirō Hitsugaya confronts his Zanpakutō, Hyōrinmaru, who has lost his memories. Hitsugaya tries to get Hyōrinmaru to remember, but has little luck. Hitsugaya releases his Shikai against his Zanpakutō and traps both himself and Hyōrinmaru in Ryūsenka. Inside the ice, Hitsugaya calls out Hyōrinmaru's name, causing the Zanpakutō to remember. Hyōrinmaru breaks the ice and gently carries Hitsugaya out. Elsewhere, Ichigo runs into Momo and Rangiku who are taking their Zanpakutō Spirits away. Muramasa then appears out of a Garganta and Ichigo goes to fight him before being confronted by Senbonzakura. After Senbonzakura releases Bankai, Ichigo figures out that it is Byakuya's Zanpakutō. The two fight and Ichigo manages to gain the upper hand before Byakuya appears. Byakuya stops Senbonzakura from attacking Ichigo before he himself does so. He tells Ichigo that he will do if he tries to impede Muramasa's plans and they head off. The next day, the news of Byakuya's betrayal goes out, shocking many and upsetting Rukia.

At the Zanpakutō cave, Byakuya enters, much to the surprise of the other Zanpakutō Spirits. He is questioned as to why he is there and says he does as his pride dictates. Muramasa then gives him a challenge to prove his loyalty. He must kill Sode no Shirayuki, his sister's Zanpakutō. Though the Zanpakutō Spirits initially believes that they have him trapped, Byakuya does not hesitate and attacks Sode no Shirayuki. She puts up a minor fight, but Byakuya makes quick work of her by binding her with Kidō and slashing across her, reverting her to a sword. Muramasa tells Byakuya that he has a job for him. Late at night, Rukia awakens in Byakuya's office to find many unconscious Shinigami on the ground. Byakuya stands before her and tosses the broken Sode no Shirayuki at her. He tells her to stay away, but as she asks what he means, Senbonzakura swings at her. Renji appears to stop Byakuya. He tries to use Shikai, but Byakuya says he shouldn't be able to. Zabimaru appears, but Senbonzakura stops their attack. Renji and Byakuya relocate to the roof to continue their battle as Senbonzakura and Zabimaru continue in the building. Though the lieutenant and his Zanpakutō both initially overwhelm their opponent, Byakuya and Senbonzakura gain the advantage and defeat their opponents. Many other Zanpakutō Spirits arrive as Onmitsukidō arrive to take control of the situation along with several other Shinigami and Ichigo.

The Shinigami each take a Zanpakutō. Fifth Seat, Yumichika Ayasegawa finds his own Zanpakutō Spirit, Ruri'iro Kujaku and after initially being drained by his Shikai ability, he defeats the Zanpakutō Spirit and returns it to its sword form. Elsewhere, Ikkaku faces Hōzukimaru one last time. The Zanpakutō Spirit uses Bankai, but Ikkaku reminds him of his strength and position and the two charge at each other before Hōzukimaru collapses, defeated, along with Ikkaku due to his injuries. On the rooftops, Suì-Fēng encounters Captain Komamura's Tenken and Lieutenant Sasakibe's Gonryōmaru. Though the two put up a fight, Suì-Fēng activates her Shūnko to knock Gonryōmaru back and stop Tenken's attack. Meanwhile, Lieutenants Isane Kotetsu and Tetsuzaemon Iba run into Captain Mayuri Kurotsuchi's Ashisogi Jizō. Along with Rangiku and Momo, they run from its deadly poison and blades before being incapacitated by it when it goes into Bankai. After saving Hisagi, Kira faces his friend's Zanpakutō, eventually knocking him out with an explosive armband and Kidō, but Kira is then knocked out by his own Zanpakutō, Wabisuke and only saved by the arrival of Captain Kenpachi Zaraki. Back at the barracks, Ichigo fights Senbonzakura. The two put up a fierce fight with neither injuring the other, but as Ichigo goes to attack Senbonzakura after a decisive hit, he finds his opponent is not there and is swallowed by Ashisogi Jizō's poison, causing him to collapse.

Having gone up against two Zanpakutō Spirits, Suì-Fēng finds a Homōnka on her back. She initially doubts that the spirit before her is her own Zanpakutō Spirit, but the Suzumebachi offers to sting Suì-Fēng again in the same spot and see what happens. Just then, Kenpachi Zaraki arrives and Suì-Fēng berates him for coming so late. He unleashes a surge of Reiatsu, sending Suì-Fēng and her Zanpakutō Spirit flying. Continuing from where the left off, Suzumebachi taunts Suì-Fēng and goes to attack her. Suì-Fēng activates her Shūnko to stop the attack and manages to sever the Zanpakutō Spirits stinger from her body, ending the fight. Suì-Fēng collapses from exhaustion, but Yoruichi Shihōin arrives to catch her and informs Suì-Fēng that she has found Captain-Commander Genryūsai Shigekuni Yamamoto. Meanwhile, Kenpachi encounters Byakuya. Commenting that he has always wanted to face the captain, Kenpachi makes the first move slashing at Byakuya. The two continue to clash with Byakuya using his Shunpo abilities to escape Kenpachi's powerful attacks. After seeing Kenpachi's fierce determination, Byakuya finally decides to have a real match with him, but the ground around them crumbles as Ashisogi Jizō reappears and Byakuya leaves. Kenpachi grabs it and yells at it for interrupting his fight, but Mayuri soon appears and detonates the Zanpakutō Spirit, returning it to its unreleased state.

Middle Stages
After the confrontation with the many Zanpakutō Spirits, Captain Retsu Unohana appears and begins the healing process. Kenpachi tries to go to find Byakuya but Yoruichi tells him to wait, and that she knows where Byakuya and the Captain-Commander are. In the Zanpakutō cave, Muramasa shows Byakuya where Yamamoto is. Byakuya sees Yamamoto under a pyramid like barrier with three Zanpakutō Spirits floating above it, channeling their Reiatsu. Back in Seireitei, Yoruichi puts together a team of Captains Shunsui Kyōraku and Jūshirō Ukitake, as well as Ichigo. After some convincing by Lieutenant Yachiru Kusajishi, Kenpachi decides to go as well. They head to the cave where Kenpachi promptly goes off on his own into the cave with Yachiru cheering him on. Yoruichi tells everyone to be cautious as they then enter the cave themselves.

Inside the cave, Yoruichi and Ichigo head inwards before they are attacked by Haineko and Tobiume and separated. The two Zanpakutō Spirits team up against Yoruichi, who dodges with her incredible speed. Yoruichi is soon trapped by rocks and Haineko and Tobiume explain that they were only told to stall for time. Yoruichi then gets up and tricks the two, knocking them out. She realizes what Muramasa is after and heads further inside. Elsewhere Shunsui and Ukitake run into their Zanpakutō Spirits, Katen Kyōkotsu and Sōgyo no Kotowari. The two captains head off in different directions with their Zanpakutō Spirits and manage to handle them without much difficulty. After regrouping, they realize that the Zanpakutō Spirits were not trying to harm them, but rather they were stalling. The two captains then get around the Zanpakutō Spirits and continue further into the cave, realizing Muramasa is after Ichigo's ultimate attack. After getting lost for a while, Kenpachi and Yachiru enter a den where they are confronted by Tenken and Gonryōmaru. After making quick work of Gonryōmaru and realizing that they are not using their full power, Kenpachi faces Tenken one on one. After catching the giant's sword one handed, Kenpachi taunts Tenken, who then releases his Bankai, breaking through the roof and becoming the giant of Komamura's Bankai. Kenpachi becomes excited and leaps up after him.

After being separated from Yoruichi, Ichigo encounters and chases after Captain Retsu Unohana's Zanpakutō, Minazuki, who escapes away from him. He continues on before encountering Kazeshini whom he promptly defeats with a point blank Getsuga to his face. Ichigo carries on to the top of the cave where he runs into Muramasa. Ichigo engages the Zanpakutō Spirit in battle and Muramasa taunts Ichigo, telling him to use his ultimate attack. Obliging him, Ichigo dons his Hollow mask and fires a Getsuga at him. Yoruichi, Shunsui, and Ukitake arrive to late to stop him and the attack breaks open the barrier surrounding Yamamoto. Ichigo is informed of what he has done and Yamamoto gets up and declares that the Shinigami have lost this round as Ryūjin Jakka bursts forth, destroying the cave. Yamamoto reveals that he placed himself within that barrier to keep Muramasa from getting Ryūjin Jakka. Yamamoto informs everyone of who Muramasa is and who his owner was, saying that he had led a revolt and that Muramasa did not kill his owner, but was after the method to free him, which only Yamamoto knew of. Surrounded by flames and needing to get out to stop Muramasa, Ichigo tries to break out, but is stopped. Suddenly, Hitsugaya and Hyōrinmaru arrive and freeze Ryūjin Jakka's flames long enough for Ichigo to get out.

Later Stages
Muramasa escapes to the Human World, but is coughing up blood, and he soon collapses. When he awakens, he sees Orihime Inoue healing him. They are then interrupted by the arrival of Uryū Ishida and Yasutora Sado. Muramasa dodges their attacks and Senbonzakura arrives to aid Muramasa before Rukia makes an appearance to knock him back. Soon, Muramasa reveals his true purpose and unleashes many Hollows. As Uryū, Sado, and Rukia fight the Hollows, Muramasa accomplishes his goal and releases Kōga Kuchiki from his prison and Ichigo arrives too late.

Now released, Kōga shocks everyone by snapping his Zanpakutō in half, forsaking Muramasa. As he goes to kill his Zanpakutō Spirit, Byakuya steps forward to stop him. Senbonzakura then reveals to Ichigo and Rukia that he and Byakuya have teamed up since the beginning in order to stop Muramasa and prevent Kōga from being released. Senbonzakura returns to his sword and Byakuya attacks Kōga, but soon finds himself caught by Kōga's illusion powers. After Kōga traps Byakuya, Senbonzakura frees himself to save Byakuya, shocking Kōga. Byakuya uses Senkei before activating his final attack as he charges at Kōga one last time. As water that was up heaved by the clash clears, Byakuya stumbles, but Kōga falls into the lake below, dead.

Having been abandoned by his master, Muramasa loses control of the multiple Hollows that he had been storing inside of him and unleashes countless Gillian in to the area. Everyone unites to defeat them before Muramasa loses control and takes on a Hollow like form. Ichigo manages to slightly overpower him with his mask, but the many Gillian make the fight tougher. Soon, Muramasa loses all control of his Reiatsu and is enveloped by a large dome like structure as a Garganta opens, unleashing hundreds more Gillian. As the situation looks grim, the Zanpakutō Spirits, recently freed from Muramasa's control, arrive to team up with the Shinigami and force the Garganta to close.

Having been enveloped in Muramasa's Reiatsu, Ichigo finds himself in Kōga's inner world where he finds Muramasa in his normal state. Muramasa brings forth his sword as he attacks Ichigo. Muramasa traps Ichigo with his spirit threads, but a pillar falls, disrupting the attack and allowing Ichigo to use a Getsuga Tenshō to completely sever the threads. Muramasa uses more illusions to fight against Ichigo, but he sees through the attacks and sends Muramasa flying through several pillars. Ichigo berates Muramasa on his beliefs, but the Zanpakutō Spirit will not give up and his Hollow mask begins to form on his face. Ripping it off, Muramasa charges at Ichigo for a final time, falling in the aftermath.

Aftermath
The dome fades away as Muramasa falls defeated. The Shinigami and Zanpakutō defeat the mass of Hollow and Ichigo stands over Muramasa who dies mid sentence and fades away. Ichigo confirms everyone is okay and the Zanpakutō return to their swords. Byakuya thanks Ichigo and Ichigo accepts before Byakuya's thanks before he leaves. With many Zanpakutō wielders dying during the attacks, many Tōjū are left in the wake.