Royal Training is an event that takes place during the Quincy Blood War. It revolves around Ichigo Kurosaki being invited to the Royal Palace and trained by the Royal Guard in preparation for the war between the Gotei 13 and Wandenreich.
After the devastation during Fall of the Seireitei caused by the Wandenreich, the Royal Guard arrive. They point out that their mission is to rebuild the Gotei 13 and bring Ichigo Kurosaki, his broken Bankai Tensa Zangetsu, Rukia Kuchiki, Byakuya Kuchiki and Renji Abarai back with them to Soul King Palace to rehabilitate and train them.  After a short conversation with the assembled Captains of the Gotei 13, they go back to the Soul King Palace with their targets. 
When they arrive to the palace Ichibē Hyōsube tells Ichigo that he should feel honored he's permitted to go there, before pointing out he isn't exactly an ordinary Shinigami. As Ichigo looks around at the palace and thinks this is the place Sōsuke Aizen tried to come to, he suddenly realizes they should have needed to use the Ōken to enter. Ichigo asks when they used the key, to which Hyōsube responds by showing him his arm and explaining that the Soul King has the power to turn the very bones of the Royal Guard members into the Ōken so the only way to enter the palace is to come with them or have their permission. Thus Aizen tried to create his own Royal Guard, technically speaking. Senjumaru Shutara notes that while Aizen tried to create life, kill the king and achieve godhood, that the evil of the Wandenreich surely surpasses his.
Ichigo, standing on a platform, is told to stand still when they catapult him up or else he'll die. As Tenjirō Kirinji is just about to shoot him up, Ichigo questions what he's doing and asks if he is going to see the Soul King. Kirinji questions Ichigo's sanity, asking if he's really so dumb that he believes he's actually allowed to meet the Soul King. He is however hit on the head by Kirio Hikifune before he can continue.
Hikifune goes on to explain the layout of the palace to Ichigo, with each of the flying disks having a city on it with each belonging to a different member of the Royal Guard and the Soul King residing in the Greater Soul King Palace in the middle. Kirinji then points out that they will go to his palace first. 
Hot Spring Demon
In Kirinji's palace, the Kirinden, Ichigo and Kirinji bathe in a hot spring. Ichigo, confused, complains and asks why he is there. Kirinji simply tells him not to drop the towel on his head. After Ichigo once more asks him why he is there, he says they are there to bathe, but he is interrupted by Byakuya floating up next to him. After pushing Byakuya underwater again, Kirinji responds to Ichigo's complaints about Byakuya being there by showing him that Renji and Rukia are also there underwater. 
Kirinji tells Ichigo they are there to heal and explains the functions of White Bone Hell and Blood Pond Hell before throwing Byakuya into the latter. Explaining how his healing process works, Kirinji reveals to Ichigo that Kisuke Urahara modeled the hot spring in his and Yoruichi Shihōin's secret playground after his. Ichigo, dropping the towel on his head, is reproached by Kirinji about this as he will die if he doesn't keep it on. Meanwhile, the Soul King awakens. 
Later, Ichigo is being held underwater by two of Kirinji's subordinates, Kazuo and Kazuhiro as they count to a one hundred. Ichigo, almost drowns, but breaks free and comes back to the surface. Ichigo and Kirinji argue a little before Kirinji orders his subordinates to hold Ichigo beneath the surface again. After a short struggle Kirinji steps forward and hits Ichigo, sending him flying a distance away. Angered, Ichigo asks him why he did so, prompting Kirinji to respond Ichigo is now fully healed. He holds up the towel which fell off Ichigo's head and tells him he would have died otherwise.
Kirinji states he will now send Ichigo to the next palace, but before they can proceed Renji rises from the water and says he's coming too. Kirinji tries to throw Renji away as well, but Renji endures his punch. Surprised by this, Kirinji says he's healed and tells Kazuo and Kazuhiro to send the two to the next palace. As they are catapulted away, Ichigo wonders if this is the only means of transportation in the Royal Palace.
After the two have left, Kirinji gives Kazuo and Kazuhiro permission to remove their protective clothes, revealing they are badly burned. Hearing his subordinates' comments on how well Renji and Ichigo endured the springs, Kirinji reveals Ichigo actually did counter his blow and even managed to fracture his wrist, before remarking he really understands why the Soul King is so interested in him. 
Ruler of Grain
Falling through the air, Ichigo and Renji argue about who's going to take the hit when they make contact with the ground. However, they find Kon who was hidden in Ichigo's Shihakushō, who accidentally transforms into a larger form and softens the impact. Ichigo and Renji argue a little and speculate about why Kon was there before Kirio Hikifune comes and welcomes them to her palace, the Gatonden. Having been accidentally knocked down by Hikifune's greeting, they wonder if all the people in the palace are weird.
Once inside, Hikifune arranges a feast for them. Kon, entranced by the looks of the food, tries to eat it but is stopped by Ichigo who is suspecting some hidden catch. Hikifune, telling Ichigo he has become paranoid due to spending too much time with Urahara, states her palace is a palace of food before inviting them to eat as much as they want. As Hikifune starts preparing dessert, they start eating and find the food to be extremely good. After a while Ichigo, taking a break from eating, questions if it really is ok for them to be eating while everyone else is training for war. Renji responds, saying all they do in the palace prepares them for the battle. Hikifune emerges from her kitchen, having become a lot thinner much to the surprise of her guests, and tells Renji he is right. Saying what they're doing is normal training for a battle, albeit done on the Soul King's scale, she invites them to begin eating dessert.
They are still confused by who this thin & attractive woman is by time they go to the next palace, Hikifune reveals that she uses up all her Reiatsu when cooking so she has to become fat between feasts. She goes on to tell them that every member of the Royal Guard has made some contribution to Soul Society recognized by the Soul King as important, she herself having invented the theory of inserting foreign Reiatsu into a body, thus creating the Gikongan. She also utilizes this concept in her cooking, imbuing the food with Reiatsu and thus strengthening those who eat it. She warns them about the next palace, where they will encounter Ōetsu Nimaiya, the unpredictable inventor of the Zanpakutō. 
God of the Sword
Ōetsu Nimaiya, standing in a dark room, is informed by his subordinate Mera Hiuchigashima that Ichigo and Renji have arrived. Meanwhile, they, having used Kon as a cushion again, wonder why no one is nearby. As Kon starts complaining, a number of spotlights are lit around them and a voice is heard welcoming them to the palace. Ōetsu Nimaiya appears, introducing himself as the number one Zanpakutō creator. He leads them to Galaxy Hōōden, where they are greeted by many beautiful women, much to Kon's pleasure, though the other two are suspicious. Nimaiya subjects them to an elaborate ritual designed to humiliate them, they are however interrupted by Mera who tells her master to be serious and begin. Going to the real Hōōden, Nimaiya is seemingly embarrassed by the humble state he lives in. Kon, screaming he wants to go back to Galaxy Hōōden, is told by Nimaiya that they understand each other. 
As Ichigo and Renji enter the building, they quickly notice the absence of a floor and fall down a large pit. Telling them everyone they have met in his palace so far except for him are Zanpakutō, the Royal Guard member remarks on how grave it is they can't notice the difference before taking out the broken remnants of Tensa Zangetsu and Zabimaru. Smashing the Zanpakutō even further, Nimaiya notes how sad it is when Shinigami don't love their Zanpakutō and how easily they break if they're not loved. As Ichigo and Renji notice they're surrounded by menacing eyes, Nimaiya says the wrath of the Zanpakutō is all around them, further saying he will reforge their swords if they can get out of there.
Ichigo and Renji, wondering what is around them, are surprised when Nimaiya reveals to them they’re surrounded by the strongest Zanpakutō, "the Asauchi", who can become anything. The spirits then converge on them. As the two defend against the advancing Asauchi, Nimaiya explains that every single Shinigami is issued an Asauchi made by him, which they imprint their souls on and thus make their own. Still unable to comprehend, Ichigo asks if what they’re being attacked by are the embodiments of the Asauchi and why. Nimaiya says Ichigo is close to the correct answer, but not quite there yet. He further clarifies that the Asauchi are angry with them because of how they treat their Zanpakutō. He goes on to ask which is superior, the Shinigami or the Zanpakutō.
After three days and three nights, the battle is over. Renji, still standing, is told by Nimaiya that he passed and will have his blade reforged. While Ichigo, lying defeated, is told by Nimaiya his Zanpakutō will not be fixed. Ichigo, begging for another chance, is refused by Nimaiya who tells him to go home since the Asauchi did not choose him. The Royal Guard further calls him a fake Shinigami and tells Ichigo never to return to Soul Society. Ichigo, angered by Nimaiya’s words, is sent away from the Soul King Palace by Nimaiya using Kidō. After Ichigo disappears, Nimaiya remarks on how serious it is that he could get a Zanpakutō without an Asauchi and says he must go back to his roots.  Stating he thought Renji would have been more upset by this, Nimaiya says Renji realized it was useless for Ichigo to even try some time ago. Revealing he knows the location of all Asauchi he’s ever forged, Nimaiya says no one has ever managed to get a Zanpakutō without one of his Asauchi. Therefore, this method would never work for Ichigo, and that’s why he must return to his roots. 
Ichigo now back in Karakura Town confronts his father who tells him about how he met Ichigo’s mother, Ichigo is then taken back to the palace by Mera, who explains the Chōkaimon Nimaiya used to send Ichigo to the Human World needed to have a time of return set beforehand, and Nimaiya thought if he couldn’t do it in one night he would never be able to. Nimaiya again pits him against the Asauchi, however, now all the Asauchi kneel to him. Ichigo moves forward and chooses one of them. With Ichigo grasping its hand, the Asauchi takes on the appearance of Ichigo with a Hollow mask. Nimaiya, recognizing Ichigo’s success, says they can proceed now. 
After taking a slide to a large forge beneath the cliff his palace resides on, Nimaiya commends Ichigo for going first, prompting Ichigo to note that Nimaiya threw him down first. Nimaiya, showing Ichigo the waterfalls beneath, tells him he needs all the water to forge Zanpakutō before saying Ichigo will need to bid Zangetsu farewell now. Nimaiya, declaring the show can start now, is beaten to the ground by his bodyguards. Lying down, Nimaiya tells the Asauchi to come as well, causing it to dematerialize and come to him.
As Nimaiya and his bodyguards begin the forging process, he asks what Ichigo is thinking about. Ichigo wonders why Nimaiya took off his sunglasses just when he was about to begin forging, which he says was so as to see the colors of the flame. He proceeds to ask Ichigo if he ever noticed that his inner Hollow is his real Zanpakutō, further elaborating that his inner Hollow was created from White, who was created in a manner very similar to how he makes his Asauchi. Nimaiya then asks Ichigo if he does not recognize the one he thought to be Zangetsu as someone else he saw recently, as someone he faced on the battlefield, revealing him to be the source of Ichigo’s Quincy powers bearing the appearance of Yhwach from a thousand years ago.
Remembering the feeling he had of being summoned to Yhwach’s location when he arrived in Soul Society, Ichigo realizes he was reminded of someone else when he first saw him. Responding to Ichigo’s questions about him, Zangetsu says it is as he was just told and his name is not Zangetsu. As Ichigo’s inner world starts collapsing, he asks the old man if he really is Yhwach. Receiving a vague answer about him both being Yhwach and not, Ichigo questions him about whether he’s an ally or a foe and if he always lied to him. Answering he is neither, the impostor Zangetsu says his only lie was when he told Ichigo his name. Elaborating on how he always used the power of the real Zangetsu to train Ichigo and how it was always the Hollow who saved him, the old man states his only wish was for Ichigo not to become a Shinigami so he would not be hurt, therefore he always suppressed Ichigo’s potential.
Voicing his previous resolve about killing Ichigo were he ever to become a Shinigami, Zangetsu manifests a sword. Explaining how his heart changed as he watched Ichigo grow and how he eventually began helping him, the old man begins to crumble away. As he fades away, he tells Ichigo he is happy to step aside now and sheds a tear. Telling Ichigo he will no longer suppress him, the Quincy spirit encourages him to take hold of the real Zangetsu which he just manifested and fight with all his strength and not only the small part he couldn’t suppress.
Realizing none of the two spirits ever lied to him and that his Quincy powers helped him on many occasions, Ichigo decides he does not care who Zangetsu is and decides that though they may say it’s untrue, both spirits are his Zanpakutō. Ichigo, takes hold of the Asauchi Nimaiya is forging, making Hasuka Hashihara ask what he’s doing and warn him he’ll burn himself. Nimaiya calms her, saying it is all right, he tells Ichigo to pull out his sword.
As Ichigo draws the sword, the entire ocean around evaporates. Tokie Tonokawa asks if something of the sort has ever happened before, to which Nonomi Nomino responds it never has. Nimaiya, putting on his sunglasses, asks Ichigo if he will be all right with his two Zangetsus. Ichigo, feeling both spirits in his Zanpakutō, resolves not to ask Zangetsu for power or not to get in his way. Thanking Zangetsu, he thinks from now on he’ll fight for himself, realizing Zangetsu is him.
Great Weave Guard
In Senjumaru Shutara's palace, Renji and Rukia are being measured for new clothes. Asking Renji to remove his fundoshi so she can measure him completely, Senjumaru threatens to cut off a certain part of him when he does not comply, resulting in his immediate compliance. 
Monk Who Calls the Real Name
Engulfed in intense training, Renji and Rukia eventually lose their concentration. Renji, falling to the ground and exclaiming the training is hard, is rebuked by Rukia who says training which simply involves them looking at each other silently can't be so difficult. Renji notes how he dislikes standing still and pointing a sword at an ally, and then goes on to point out Rukia is tired for the same reason he is.
After agreeing with Renji's statement that they're not used to the dense atmosphere in Ichibē Hyōsube's palace, Rukia receives a call from Kirinji informing her of her brother's recovery. At the same time, in Kirinden, Kirinji tells Byakuya Kuchiki no one has ever been in his hot springs so long before and asks if he's dizzy. Byakuya, states he's not strong enough to feel dizzy, but he will regain enough strength so he can feel dizzy again.
Renji, happy by the news of his captain's progress, soon realizes Byakuya will have to go to Senjumaru Shutara's palace. Rukia tries to stop him from having a flashback, but to no avail, as Renji remembers what was done to him in the previous palace. With Renji regaining composure, Rukia tells him to be glad he only had his flashback up until before he had to undress. Expressing how sad she is Byakuya will need to be treated the same way, Rukia and Renji are surprised by Ichibē emerging from his palace, laughing. He notes how talkative they have become compared to when they arrived there and couldn't even move due to the Reishi density, before inviting them to train with him in the inner room. The two readily accept his invitation. 
Inside, Ichibē reveals to Renji that his Bankai's name is a lie, or rather his Zanpakutō never told him its full name, meaning that Zabimaru doesn't fully acknowledge Renji. Renji, having difficulty accepting this, is surprised when Ichibē says he's going to tell him the true name of Zabimaru's Bankai. Clarifying the true meaning of his title, Monk Who Calls the Real Name, Ichibē reveals he can see the true name off things, further revealing he was the one who chose the names of everything in Soul Society. Telling Renji the true name of Zabimaru's Bankai, Sōō Zabimaru, Ichibē states Renji must now convince Zabimaru to allow him to call it by that name. 
Later, Kirinji asks Ichigo if he is ready to leave, to which he responds he is. Ichigo, clad in new clothes, becomes confused and starts looking for the Tenchūren. Kirinji questions what he's doing and tells him he's going to walk to Seireitei. After Senjumaru makes a spiral staircase appear, Kirinji says the Royal Guard can't use the Tenchūren all the time and tells him he will arrive in Seireitei in only a week using average Shunpo. Anticipating a shocked reaction, Kirinji is surprised when Ichigo calmly agrees and states he will be in Seireitei in only half a day if he hurries.
Laughing, Ichibē approaches them. Saying Ichigo doesn't have to worry about reaching Seireitei in time for the battle, he reveals the Wandenreich's attack begun three hours ago. Greatly annoyed by this piece of news, Ichigo immediately dashes away as he shouts to Ichibē he should tell him such things earlier. Ichibē dismisses this because Ichigo was still in training three hours earlier. Hikifune comes and asks where Ichigo is. After hearing he has already left, she throws a rice ball to him, which he happily accepts.
Hikifune and Kirinji remark on how strong Ichigo has become, causing Ichibē to say this is not the case, and rather he has become strong. When Kirinji points out that is exactly the same, Ichibē elaborates on how not only has Ichigo become more powerful but rather he has become stronger in both mind and body and goes on to state he has become a true Shinigami.
While travelling to Soul Society, Ichigo calls Urahara and informs him he's on his way. After asking Urahara to make sure Soul Society survives until he can get there and save them, Ichigo puts down the phone, notes Urahara said nothing about the condition of Seireitei and says he must hurry before increasing his speed. 
Renji and Rukia, on their way towards Soul Society, discuss tactics  and note they should get there before night falls.  Once they arrive, Renji confronts Mask De Masculine  and Rukia later encounters Äs Nödt.  Byakuya arrives later and assists Rukia.