A mysterious man who calls himself "Muramasa" appears in the Seireitei to declare war against the Soul Reapers. Using his powers, Muramasa gives physical form to the Zanpakuto and liberates them from the captains and lieutenants of the 13 Court Guard Squads.

Having sustained severe injuries in battle, Rukia escapes to the World of the Living and is saved by Ichigo. A mysterious woman then arrives through the Senkaimon and proceeds to attack the two using the same Zanpakuto as Rukia.

After hearing that Byakuya has gone missing, Rukia returns to the Seireitei to search for her brother and in the process comes across Sodenoshirayuki.

Muramasa appears before Ichigo and explains how he freed the Zanpakuto from the Soul Reapers, as well as gave them a physical form to exist.

The Zanpakuto rebellion has left the Seireitei in a state of destruction with many Soul Reapers still missing, including Squad Six captain Byakuya Kuchiki.

Inside Ichigo's mind, Muramasa meets Hollow Ichigo. Taking an interest in him, Muramasa attempts to manifest Hollow Ichigo like he did with Zangetsu, only to discover that his spell does not work on Hollow Ichigo.

Ichigo has regained his Shikai and battles Muramasa. But Zangetsu, who has sided with Muramasa, steps in to fight Ichigo.

Ichigo's and Renji's victories against their own Zanpakuto has proven that a Soul Reaper can reclaim his Zanpakuto by defeating it in battle.

Haineko and Tobiume, two Zanpakuto who do not get along, are walking through the woods when they spot Ichigo, who is in pursuit of Senbonzakura and Byakuya.

The battle of Rangiku and Momo versus Haineko and Tobiume heats up, as both sides try to outsmart their opponents. Elsewhere, captain Toshiro Hitsugaya has located his Zanpakuto Hyorinmaru. But to Toshiro's surprise, Hyorinmaru has lost all trace of his memory following his release by Muramasa. In order to help regain Hyorinmaru's lost memories and prove that he is it...

Results from Mayuri Kurotsuchi's experiment using Marechiyo Omaeda's Gegetsuburi show that a manifested Zanpakuto cannot revert to its original sword state when defeated by someone other than its master.

The Thirteen Court Guard Squads, particularly Renji and Rukia, are shocked by the news of Byakuya now supposedly working with Muramasa. Meanwhile, inside Muramasa's hideout, the Zanpakuto cannot hide their discomfort over having Byakuya join them.

At the Squad Six Barracks, Renji and Rukia are determined to know why Byakuya has betrayed the Soul Society to work with Muramasa. Their conversation is cut short by the arrival of the manifested Zanpakuto.

The Soul Reapers find themselves in a tough battle against the manifested Zanpakuto, including Ichigo who is struggling against Senbonzakura.

The battle between Soul Reapers and Zanpakuto heats up as Kenpachi joins in the fight. Kenpachi easily overwhelms the Zanpakuto with his incredible Spirit Energy and then goes off to challenge Byakuya.

Ichigo, Renji, Rukia, and Izuru collapse after being exposed to Konjiki Ashisogijizo's poison. Konjiki Ashisogijizo then seeks for its next prey but is stopped by Yachiru Kusajishi.

Yoruichi has located Muramasa's hideout where Head Captain Yamamoto is being held. A team comprised of Ichigo, Shunsui, Jushiro, Kenpachi, and Yoruichi sets out to rescue the Head Captain, but the group soon encounters the Zanpakuto who were anticipating their arrival.

Ichigo battles Muramasa in order to save Head Captain Yamamoto from captivity. Meanwhile, Yoruichi, Shunsui, and Jushiro notice that the Zanpakuto are trying to prevent them from reaching Ichigo, and quickly realize that he was the key to Muramasa's plan all along.

Muramasa's true objective is revealed to be in Karakura Town. Ichigo and the other Soul Reapers try to go after Muramasa, but the manifested Zanpakuto of Genryusai's Ryujinjakka stands in their way.

Uryu, Chad, and Orihime confront Muramasa who has entered the World of the Living. Using teamwork, Uryu and Chad at first appear to gain the upper hand in battle, when Senbonzakura appears to assist Muramasa.

Centuries ago, Ginrei Kuchiki, Byakuya Kuchiki's grandfather, and his son-in-law Koga Kuchiki were assigned to bring down the rebel forces threatening the Seireitei. With his Zanpakuto Muramasa's power, Koga wipes out the renegade Soul Reapers one after another, and soon his strength becomes known throughout the Soul Society. Yet Koga himself was frustrated by the fac...

Koga Kuchiki escapes his confinement and in the process, kills the Soul Reapers who framed him. Although Ginrei sympathizes with his son-in-law's situation, he reprimands Koga for his rash actions. Enraged, Koga severs his ties with the Kuchiki clan and begins killing Soul Reapers and innocent people.

To uphold the honor of his family, Byakuya Kuchiki fights the resurrected Koga Kuchiki. Meanwhile, the despair of being abandoned by Koga takes its toll on Muramasa's body.

Koga's betrayal causes Muramasa to lose control over all of the Hollows he absorbed to sustain himself. To make matters worse, his immense Spiritual Pressure begins to attract other Hollows to Karakura Town. As Ichigo, Uryu, Chad, Orihime, and Rukia work together to deal with the situation, Muramasa fires a massive Cero towards them.

Uryu and the others attempt to save Ichigo, who has been engulfed by Muramasa, but with little success. Meanwhile, the Soul Reapers of the Thirteen Court Guard Squads team up with their own Zanpakuto to fight the Hollows that have appeared in the World of the Living.

Inside Muramasa's mind, Ichigo clashes blades with Muramasa. As Muramasa's body and mind reach their limits, he begins to transform into a Hollow. With little time remaining, Ichigo and Muramasa decide to settle their score once and for all.

With the defeat of Muramasa, peace has returned to the Soul Society. Renji, Rukia, and the other Soul Reapers are having a good time at the Kuchiki mansion's party, when the place is suddenly attacked by two unknown beings. Having left her Zanpakuto behind, Rukia falls into danger when, to her surprise, the manifested Sodenoshirayuki comes to her rescue.

The assailants who attacked the Kuchiki mansion are identified as "Sword Beasts," manifested Zanpakuto of Soul Reapers who lost their lives during the battle with Muramasa. Due to the potential danger, an order is issued throughout the Soul Society to hunt down all remaining Sword Beasts, including ones who have escaped into the World of the Living. Toshiro, Hyorinmar...

Renji and Zabimaru (Monkey and Snake) come to the World of the Living to go after a Sword Beast. However, Snake is too distracted by his surroundings, and as a result lets the Sword Beast escape. After being scolded by Renji and Monkey, a frustrated Snake decides he wants to be his own man and runs off.

Isane and Hanataro are troubled by the recent reports of someone stealing food from the Squad Four barracks. Evidence shows that the thief is hiding in an underground waterway, and so a team comprised of Hanataro, Nanao, Ikkaku, and Hozukimaru is sent down for investigation.

Following Muramasa's defeat, most of the Zanpakuto have reconciled and returned to their masters, except for Kazeshini, who is still out to kill his former master Shuhei Hisagi. When Kazeshini goes into the Rukon District in the hopes of finding Shuhei, he instead comes across an infant who just lost his father to a Sword Beast. To Kazeshini's annoyance, the infant ha...

A new student Haida Kyoko comes to Orihime's class after a ghost attack on one of the girls in the same classroom.

During a mission to hunt down the Sword Beasts, Haineko comes across a wounded Sword Beast called Narunosuke and, to her surprise, falls in love with the handsome enemy before her. Believing that Narunosuke is different from other Sword Beasts, Haineko goes against her orders and decides to look after him.

Renji's Zanpakuto Zabimaru, consisting of Monkey and Snake, are irritated over the fact that Byakuya's Senbonzakura is taking all the credit for their work. Later, a small accident leads to the three Zanpakuto becoming trapped inside the Department of Research and Development's facility. As they try to find a means to escape, the two Zabimarus find Senbonzakura to be ..

Lieutenant Nanao Ise is paired up with Katenkyokotsu Wakizashi, the shorter of Captain Kyoraku's two swords, to hunt for Sword Beasts. But Nanao finds Wakizashi's malicious and distrustful nature to be quite difficult to work with.

The Zanpakuto notices the remaining Sword Beasts acting strangely and realizes it to be the work of Kirikaze, a Sword Beast capable of robbing Spirit Energy from others. With their time to manifest as physical entities reaching their limits, the Zanpakuto is determined to carry out their last mission to defeat Kirikaze.