Ichigo Kurosaki & Hollow Ichigo vs. Zangetsu & Muramasa

is a battle in the Zanpakutō Rebellion wherein Muramasa released the spirit of Zangetsu in order to fight Ichigo.

Prologue
After Rukia finishes her fight with Sode no Shirayuki, Ichigo is confronted by Muramasa who reveals himself to be a Zanpakutō spirit. When Muramasa reveals that he knows Ichigo's name, Ichigo asks how he knows this. Muramasa says that it is not important but that his goal is to free all Zanpakutō spirits from Shinigami control. Ichigo becomes angered by this and yells at Muramasa, asking how to return Rukia's Zanpakutō back to normal. Muramasa instead asks his own question, what are Zanpakutō? Ichigo is confused by this and Muramasa states that a Zanpakutō is a soul born within their Shinigami's heart and they share the same Reiatsu as their Shinigami, therefore they are always within their Shinigami. Muramasa then explains the development of Zanpakutō's, detailing the process through which Shikai and Bankai are achieved. Muramasa then says that a Zanpakutō does not have to live in symbiosis with their Shinigami. Ichigo asks what this means and Muramasa reveals that Zanpakutō's have wills of their own. Ichigo is shocked to hear this. Muramasa then says that Zanpakutō's have their own souls that are just as important as a Shinigami's. When Ichigo expresses disbelief, Muramasa says that that is what makes Shinigami so arrogant. Ichigo tries to counter this but Muramasa continues, saying that he understands Zanpakutō's and can reach out to their souls. Those who commiserate with his plan take own their true form. Ichigo calls this impossible but Muramasa says that any Zanpakutō that answers his call becomes an entity separate from their Shinigami.

Ichigo angrily asks why Zanpakutō listen to him and Muramasa says that it is their desire, stemming from the Shinigami's oppression. Rukia then manages to get out a few words, saying she has never looked down on Sode no Shirayuki. Muramasa says that she is alone in that opinion as Sode no Shirayuki answered his summons. As Rukia begins to lose strength again, Muramasa tells her that her part is done, making Rukia question him. Muramasa explains that he will free every Zanpakutō from their Shinigami, no exceptions. In order to do so, he helped Rukia get to the Human World to bring Ichigo back. Ichigo says that Muramasa will not get away with this and says they should change locations. Muramasa agrees and they head off. Ichigo attacks Muramasa who summons his sword and defends. Muramasa unleashes an attack and Ichigo counters with a Getsuga Tenshō, which Muramasa easily evades. As he searches for the Zanpakutō spirit, Ichigo begins to see the world warp around him. Muramasa then calls out to Ichigo, telling him to sheathe his sword. Ichigo tries to attack different areas to find Muramasa but the world around him soon begins to spin. After falling down, he is pulled forward and pinned to the ground. Muramasa then reappears and kicks Ichigo's sword away. He sticks his hand out and begins to recite a chant. As he does so, Ichigo spins in place and a dark energy appears around him. When he finishes the chant, Muramasa reaches into Ichigo's chest and pulls out a chain as smoke fills the area. When the smoke clears, the manifested spirit of Zangetsu appears next to Muramasa before attacking Ichigo.

Battle
Zangetsu pushes Ichigo back and Ichigo asks Zangetsu what is going on. He asks if they were not of one body and soul but Zangetsu does not answer. Zangetsu then appears behind Ichigo and knocks him into the wall before firing a Getsuga Tenshō at him. Muramasa walks over and is surprised to see that Ichigo could still move but says that it does not matter as the fight is already over. Ichigo manages to get to his knees and asks Zangetsu if he is really serious about this. Zangetsu responds by firing another Getsuga at Ichigo. As the smoke clears from Zangetsu's attack, Ichigo stands before Zangetsu and Muramasa with half of his mask on and grinning. He opens his eyes, revealing that Hollow Ichigo has taken over. He lunges at Zangetsu and perpetually knocks him back with a series of hits. Zangetsu recovers and prepares to counter but Hollow Ichigo evades and grabs Zangetsu by the face and throws him back into a wall. Muramasa then asks who he is and Zangetsu says that that is another soul that resides in Ichigo. Zangetsu fires another Getsuga but Hollow Ichigo counters with his own. Hollow Ichigo goes to attack again and Zangetsu evades multiple time, moving the fight elsewhere. As Hollow Ichigo's attacks continue, Zangetsu effortlessly dodges before countering and cutting his opponent across the chest. However, the wound quickly regenerates and Zangetsu attacks again, cutting Hollow Ichigo across the shoulder sending Hollow Ichigo to the ground squirming. However, a large creature appears from the wound and attacks Zangetsu. Zangetsu dodges initially but is swallowed in the second attack.

Zangetsu manages to break out but Hollow Ichigo emerges, now having taken over more of Ichigo's body. A swirling black Reiatsu surrounds Hollow Ichigo which then envelops him and explodes. When all settles, Hollow Ichigo has now completely taken over Ichigo's body as lines of black reiatsu emanate from his back. Muramasa is startled by this output of reiatsu. Hollow Ichigo jumps high into the air before crashing down on Zangetsu and going into a berserk rage. Zangetsu manages to block most attacks but one slips through and cuts his arm. Hollow Ichigo then headbutts Zangetsu, knocking him back and fires a large cero from the palm of his hand. Zangetsu quickly counters with a Getsuga but it does little to stop the monstrous cero. Zangetsu is knocked far back and as Hollow Ichigo looks on, Muramasa strikes him from behind, but the wound closes up instantly. Hollow Ichigo then turns around and knocks Muramasa away. Hollow Ichigo slowly approaches Muramasa but falls down as his mask begins to crack. Ichigo calls out that he will not let Hollow Ichigo have his body and tears the mask off of his face. Blue and Black reiatsu envelops Ichigo before shooting out and destroying a large portion of the area. As the dust settles, Hollow Ichigo's body is completely cracked. It then breaks apart, leaving Ichigo in his original form. A weakened Ichigo then calls out for Zangetsu several times before collapsing.