Yhwach after killing all the guards he absorbs his father, the Soul King, and made the Soul King Palace into his territory.
When Schutzstaffel arrives, Yhwach orders them to fight the intruders, thus Schutzstaffel went flying to fight the intruders.
After the Gotei 13 and their allies enter the Royal Realm, Mayuri enters separately at a different location in the city and proclaims that he is free to test the results of his research as he pleases, only to be shocked when Kenpachi appears behind him and affirms this.
Kenpachi explains how the others had left while he was using the bathroom before noting that he does not have to worry about cutting them up by accident now, prompting Mayuri to admit that this also gives him an opportunity to eliminate certain "insects" as the two glare at each other.
Eventually, Mayuri and Kenpachi accompanied by Nemu Kurotsuchi, Ikkaku Madarame, and Yumichika Ayasegawa encounters Pernida in a narrow alleyway.
When Kenpachi wonders what it is, Mayuri ponders why a member of the Gotei 13 would ask someone else for information on something neither of them have seen before.
However, Kenpachi decides to kill it and begins advancing as Mayuri and Nemu watch.
However, as Kenpachi prepares to attack Pernida, Mayuri is alerted by something and shouts for him to wait, prompting Kenpachi to leap back with a mangled arm as Mayuri expresses concern for him.
Kenpachi notes that Pernida only got one of his arms and points out how he managed to split its head open in return, but Pernida's hood begins expanding, prompting a surprised Kenpachi to wonder what it is once more.
As Pernida's hood continues to expand, Mayuri observes that it does not seem to be a battle-oriented function before admitting that he finds it creepy, prompting Kenpachi to note that he is surprised by this.
Suddenly, Kenpachi's injured arm begins to twist and contort itself even further, forcing Kenpachi to rip it off with his other arm.
After Kenpachi pries his Zanpakuto out of the grasp of his detached limb, the arm is contorted further and further until it collapses in on itself, leaving nothing more than a puddle of blood.
Mayuri commends Kenpachi for doing this unhesitatingly because his whole body would have been warped and squashed as his arm was if he had not torn it off.
When Kenpachi repeats his question of what Pernida's power is, Mayuri notes that he does not know if Kenpachi is asking him or talking to himself before admitting that he does not know.
Advising Kenpachi to keep his distance from Pernida for now, Mayuri has Nemu bind Kenpachi's arm stump with a tourniquet as Kenpachi wonders how he can kill Pernida without getting close, which prompts Mayuri to attempt to come up with a plan to do this.
Claiming that he was simply talking to himself, Kenpachi rushes toward Pernida despite Mayuri's protests and proclaims that he merely has to kill Pernida before its power can affect him before slashing partway through its body.
However, Pernida survives this attack and breaks Kenpachi's legs, prompting Mayuri to step in and stab Kenpachi through the chest with Ashisogi Jizo.
As Kenpachi looks back and curses him while coughing up blood, Mayuri notes that simply paralyzing Kenpachi's limbs causes everything else in his body to break before activating Ashisogi Jizo, Kyodo Yon, which causes the face on Ashisogi Jizo to begin leaking a dark fluid from its eyes as it begins to emit a sound from its mouth.
Nemu tells Ikkaku and Yumichika to cover their ears because they will be paralyzed if they hear the sound for more than four seconds.
As Kenpachi collapses, Mayuri pulls out Ashisogi Jizo and notes that he needs Kenpachi paralyzed because his brute strength is still useful.
Pointing out how Pernida being paralyzed as well means that The Compulsory is not linked to its main body, Mayuri reveals that Pernida sends its nerves into its opponents' bodies to forcibly control and break them.
When Pernida extends several shadowy tendrils toward him, Mayuri coats them in a liquid which exposes Pernida's nerves while claiming he has nothing to fear from this, which causes Pernida to reel back and scream in pain as its cloak begins to dissolve.
As Mayuri tells Kenpachi that he stabbed him for his own sake, Kenpachi manages to move his eyes, prompting Mayuri to admit this is impressive before noting that he will simply improve the paralytic abilities of Ashisogi Jizo.
Noting that he cannot help but feel grateful to Kenpachi for exposing the true nature of The Compulsory and giving him a reason to improve his Zanpakuto, Mayuri turns to Pernida and claims that Pernida should donate its body to him for his experiments in order to honor Kenpachi's noble sacrifice.
However, Pernida responds by tearing apart its hood to reveal a giant hand with an eye on its palm, which Mayuri identifies as the left hand of the Soul King.
As Pernida extends a large arm out of its cloak and towers over him, Mayuri notes that the left arm being somewhere on its own matches Mimihagi's past actions.
Pernida sends more shadowy tendrils at Mayuri, who merely blocks them with a strange barrier before admitting that his happiness outweighs his curiosity as to why the left arm of the Soul King is serving Yhwach.
When Ikkaku questions why he is happy, Mayuri proclaims that he has a completely new subject to research, and as Pernida extends more tendrils out from his body, Mayuri eagerly tells it to show him more.
Pernida claims it is Pernida Parnkgjas and not the left arm of the Soul King, prompting Mayuri to state he decides what its name is because he found it before deciding to simply decide the spelling instead.
Admitting it does not understand what he is saying, Pernida reasons that anything Mayuri is saying is bad because it cannot understand them before extending its tendrils into the ground and forming a large hand out of stone
Noting that Pernida can also take control of inorganic objects, Mayuri jumps back to avoid being crushed by the hand before using Jabarakaina to grab the top of a nearby tower.
However, Pernida's tendrils pursue him up the side of the tower and creating a giant stone hand out of the wall facing him, which pushes Mayuri back before seemingly crushing him with the aid of another stone hand.
When an explosion occurs between the two hands, a shocked Ikkaku wonders if Mayuri exploded, only for Mayuri to emerge unscathed while revealing that this was merely his armor exploding.
Upon hearing Yumichika warn him about touching the ground covered by Pernida's nerves, Mayuri presses a button on the heels of his shoes, causing him to stop and float in midair as discs of Spiritual Energy appear underneath his feet.
Mayuri reveals that he is using Hirenkyaku and points out how Pernida covering the ground with its nerves is meaningless if he does not step on them before blowing off Pernida's pinkie with an explosive in order to take a sample.
As Pernida screams in pain, Mayuri douses the pinkie in preserving liquid to maintain its freshness, but is surprised when an eye appears on the pinkie and unleashes more tendrils, which make their way into Mayuri's arm.
When his arm bursts, Mayuri quickly reassembles it and reveals that he has rearranged its contents before claiming that Pernida cannot control him so easily.
Mayuri admits that he has not operated on his own arm in a while, prompting Pernida to ask him if he is nervous. When Mayuri grins and asks it if he looks nervous, Pernida decides to make him more nervous.
Pernida's severed pinkie begins to sprout additional fingers and grow into a full hand before leaping toward Mayuri, who blows it back with an explosive.
As Mayuri notes that it will be difficult to take samples back with him if they keep growing, he notices Pernida ripping off its middle finger, which begins to grow into another hand itself as Pernida complains about blood getting in its eye.
Seeing this, Mayuri remembers when he read up on the functions of the Soul King's two arms as a boy, where he learned that the right arm governed stagnation while the left governed change, and admits that he never thought he would have the chance to test this knowledge himself as Pernida and two full clones of it stand before him.
When Mayuri unsheathes his Zanpakuto and prepares to activate his Bankai, Yumichika has Ikkaku move Kenpachi away because he believes Mayuri is planning to poison Pernida, but Mayuri claims this would be a waste and that he is merely using the data he has collected so far before unleashing Konjiki Ashisogi Jizo: Makai Fukuin Shotai, a modified version of his Bankai.
Mayuri explains how this modified Bankai can create a modified Konjiki Ashisogi Jizo using the information he gives it as a Konjiki Ashisogi Jizo bursts out of the Bankai and falls to the ground, where it begins screaming as Mayuri reveals that this Konjiki Ashisogi Jizo has nerves on the surface of its body.
Pernida attempts to use The Compulsory on the Konjiki Ashisogi Jizo, but the baby's skin merely peels away, prompting Mayuri to explain how it cannot be controlled because its nerves are divided into 70000 layers, each of which will simply peel away if infiltrated by Pernida's nerves.
As Mayuri taunts Pernida to take control of the Konjiki Ashisogi Jizo by infiltrating all 70000 layers in time, the Konjiki Ashisogi Jizo proceeds to devour Pernida and its clones as Nemu watches from afar.
Laughing maniacally, Mayuri asks the Konjiki Ashisogi Jizo how its stomach feels and notes that it will probably take some time for Pernida and its clones to be digested before stating that creating the Konjiki Ashisogi Jizo without teeth prevented Pernida from cloning itself further.
However, Mayuri is surprised when the Konjiki Ashisogi Jizo is torn apart from the inside out.
Leaping back, Mayuri narrowly dodges a large Heilig Pfeil, which destroys a tower in the distance as Pernida laughs before asking Mayuri if it imitated his laugh well.
With a large Heilig Bogen between its fingers, Pernida claims that Mayuri forgot it was a Quincy, but Mayuri simply states that he never thought the left arm of the Soul King would do something as embarrassing as declaring itself a Quincy.
Regenerating its fingers, Pernida asks why this would be embarrassing and claims it has always been a Quincy before noting that Mayuri's insults are annoying.
Mayuri notes that Pernida spoke more eloquently for a few seconds and realizes that its vocabulary has been growing since the beginning of their fight.
As Mayuri wonders if it is regaining its memories as the Soul King or is instead evolving for an unknown reason, Pernida forms a Heilig Bogen above each of its fingertips before firing multiple Heilig Pfeil at Mayuri, who dodges them while seeing that Pernida's nerves are connected to them.
When the nerves connected to a passing Heilig Pfeil infiltrate his left arm, Mayuri blows it off with a small explosion in order to protect himself, but the nerves on the ground bend the Heilig Pfeil and turn it around to send it back at Mayuri.
Seeing the Heilig Pfeil coming toward him, Mayuri notes that he cannot avoid it, but Nemu suddenly appears and grabs the arrow before cutting her right arm off, prompting Mayuri to grab her by the head before she can touch the ground and move them to a safe location.
After throwing Nemu against a wall, Mayuri reprimands her for acting without orders because she could have died, but Nemu states that she believed he needed protection.
When Mayuri notes that he did not teach her to fight based on her own judgment, Nemu confirms this, prompting Mayuri to claim that it would be too hard to raise the next Nemu like her before telling her to not die unless ordered to do so.
Nemu hands a regenerative drug to Mayuri and reveals that bringing it to Mayuri was her original intent when rescuing him. Injecting it into his arm stump, which grows a new arm, Mayuri notes that Nemu must have known from the beginning that he left before obtaining the drug himself, prompting Nemu, whose own arm is also regenerating, to point out how Mayuri did not search through his medicine cabinet before leaving for battle as he usually does.
When Mayuri claims that he is somewhat unsettled by Nemu watching him so closely, Nemu apologizes as the two turns to face Pernida.
Leaping off the tower they are standing on, Mayuri presses the tops of his shoes, causing them to begin firing Spiritual Energy from underneath him like rockets, as he blasts toward Pernida, who begins firing more Heilig Pfeil at him.
As Mayuri dodges the arrows, Pernida's two clones rise up behind him and form their own Heilig Bogen as all three hands unleash barrages of arrows at Mayuri, who continues to dodge the Heilig Pfeil as he contacts Nemu.
As Nemu leaps off the tower as well, Mayuri informs her that he will be spreading a highly concentrated narcotic anesthetic over the area and explains how this will render Pernida's Heilig Pfeil, if not Pernida itself, unable to move based on the strength of the nerves attached to them. Admitting that this will also affect him due to the high concentration and that he has already planned for such a situation, Mayuri tells Nemu to reach one of the Heilig Pfeil and inject the Nerve Freezing Agent into it, which will spread along the nerves to their host and paralyze their organs.
As Mayuri details how major organs will be affected, Nemu tells him he is being too loud, prompting him to tell her to be silent before explaining how he knows Pernida has blood flowing inside it, which is what will kill it.
Nemu lands on the ground and stabs one of the arrows with the agent, which spreads to Pernida and one of its clones as their skin becomes discolored.
The remaining clone sees the agent spread to its thumb as Mayuri tells it that this is the end.
However, the clone simply severs its thumb and tells Mayuri that it will take more than this to kill it.
Recognizing this way of speaking as being identical to Kenpachi's, Mayuri realizes that Pernida can mature and evolve by absorbing information from organisms that it connects its nerves too.
Kenpachi's level, Mayuri orders her to fall back as Pernida sheds its nerve-frozen skin behind him, which Mayuri recognizes as the power of his modified Konjiki Ashisogi Jizo.
Seeing this, Nemu leaps toward Mayuri with a determined look on her face, with the ground underneath her shattering as she takes off.
Nemu blasts through Pernida, who is torn to pieces by the impact, and grabs Mayuri before hurtling away.
When a shocked Mayuri demands to know how Nemu obtained this level of power, Nemu explains that she has drawn out the abilities of her Shinigami body to within 0.8% of causing her structures to collapse and that she can maintain this output for 400 more seconds.
Mayuri points out that he did not order her to do this, but Nemu states that she is following her purpose of protecting him, prompting Mayuri to angrily proclaim that her purpose is to grow and evolve.
However, Nemu merely states that she believes she can best display her growth by protecting Mayuri before throwing him onto a building below.
As Mayuri claims to feel humiliated by allowing Nemu to fight for him, Nemu confronts the remaining clone and uses Konpaku Sessaku to cut off 6% of her own soul.
After explaining that this portion of her soul will obliterate whatever it comes into contact with, Nemu fires it in the form of Gikon Jurinju, which causes Pernida's clone to warp around the blast.
The blast tears an enormous hole in the clone and splits it in half as pieces of its fingers and palm are blasted off.
Falling to the ground below, Nemu looks at Mayuri as the pieces of Pernida's clone around her suddenly sprout eyes and fingers before invading her body with nerves and tearing her to shreds.
As blood rains down on Mayuri below, the clone begins to reform itself as a shocked Mayuri expresses disbelief at what just happened.
As the two clones of Pernida crash down onto the building where he is standing, having gained mouths and more eyes, Mayuri permits them to devour Nemu's body and watches them do so before taking her brain for himself.
When one of the clones attempts to use The Compulsory on him, Mayuri repels the nerves with his Spiritual Pressure before informing the clones that they will die if they do not continue to consume Nemu's body.
One of the clones notices its body swelling up, prompting Mayuri to explain that Nemu had an organ installed in her pituitary gland that allowed her body to continue growing beyond its theoretical limitations and which was kept running smoothly by her brain.
Deciding to put it in layman's terms for the clones, Mayuri reveals consuming the organ without the brain will cause the consumer's body to be destroyed by the uncontrolled growth as the clones swell up and burst.
As pieces of the clones fall to the ground around him and explode, Mayuri walks away with Nemu's brain in his hand, only to collapse as his legs are injured.
Realizing that the clones' nerves managed to destroy his legs at the last second, Mayuri notes that this puts him in the same situation Kenpachi is in before noticing Ikkaku and Yumichika standing over him.
Mayuri claims the 11th Division is incredibly foolish before admitting that he is grateful toward them for not interfering in his fight and directs them toward somebody preservation capsules nearby.
As Ikkaku and Yumichika open the capsules to find Toshiro Hitsugaya and Rangiku Matsumoto who were killed by Cang Du and Buzz-B and later zombified by Giselle, Mayuri reveals that he managed to reverse their zombification at the cost of drastically reducing their lifespans.
Mayuri notes that they likely will not complain to the one who saved their lives as Hitsugaya thanks him before leaving.
After having Ikkaku and Yumichika place him in one of the capsules, Mayuri tells them to place Kenpachi in the other one, which they do before thanking Mayuri for saving their captain.
As Ikkaku and Yumichika leave, Mayuri expresses disgust at how many times he has been thanked today before proclaiming that he has finally created a soul which has developed on its own from the scraps he created it with.
Claiming that he has finally left Kisuke Urahara's shadow, Mayuri promises to show him the gap between them the next they meet before slipping into unconsciousness.