The Zanpakuto spirits in Bleach reside within their Shinigami's sword — as a part of the latter's soul. Their appearance, personality, and powers are all influenced by their Shinigami. It is crucial for them to find a way to coexist with each other, since if the Shinigami dies, so does their Zanpakuto. Although the Zanpakuto spirit can be usually found in their Shinigami's inner world, they have been known to make an appearance whenever they feel that their wielders need guidance.
Regardless of their origins, Zanpakuto spirits are their own person — housing unique thoughts, desires, and opinions. This means that they may not always agree with their Shinigami. In fact, Shinigami are often tested to determine whether or not they are worthy of using their Zanpakuto's powers; if they fail, they will not be able to use their blade to its fullest extent.
10 Get Along: Senbonzakura And Byakuya Kuchiki
Kuchiki Byakuya had a deep understanding of his Zanpakuto and its powers even before he met Ichigo Kurosaki. When either his Shikai or Bankai is active, his sword turns into thousands of fragments, each of which he is able to effortlessly control.
The amount of time Byakuya has spent mastering these techniques alongside his Zanpakuto clearly shows in the range of his abilities. When he loses his Bankai to Äs Nödt, he does not mourn the loss, instead saying that the experience provided him the opportunity to better understand his Zanpakuto.
9 Don't Get Along: Zangetsu And Ichigo
The Quincy half of Zangetsu is a caring mentor. He only wants to confirm that Ichigo is worthy of wielding his power, and steps in whenever Ichigo is in danger. The Hollow half of Zangetsu, however, doesn't have a good relationship with Ichigo at the beginning.
In fact, Hollow Zangetsu regularly tries to seize control of Ichigo's body in order to go on bloodthirsty rampages. Ichigo remains unaware of Zangetsu's true identity for the longest time, only realizing that he has two Zanpakutos during the Thousand Year Blood War arc. Still, it's doubtful that the three of them will ever grow close.
8 Get Along: Hyorinmaru And Toshiro Hitsugaya
The most powerful ice-Zanpakuto in Soul Society, Hyorinmaru comes to a very young Toshiro over and over again in his dreams, long before the latter even understands what's going on. Hyorinmaru tries to tell him his name each time, but Toshiro is never able to hear him until he finally goes through the training required to become a Shinigami.
When Toshiro gets his Bankai back from Cang Du, he states that it's because his Zanpakuto wants to return. After questioning the Quincy's belief that Zanpakuto don't have souls, the 10th Squad Captain welcomes Hyorinmaru back.
7 Don't Get Along: Muramasa And Koga Kuchiki
Muramasa goes to great lengths to free Koga Kuchiki, his Shinigami master who had been imprisoned for attempting to revolt against Soul Society. Unfortunately, despite Muramasa's unwavering loyalty, Koga abuses his Zanpakuto spirit and even tries to kill him.
Even this is not enough to push Muramasa away — however, the Zanpakuto spirit experiences true grief the moment Koga destroys his sword form and tells Muramasa that he is through with him.
6 Get Along: Katen Kyokotsu And Shunsui Kyoraku
Shunsui has two Zanpakuto spirits: Katen and Kyokotsu. Since they all have a mischievous nature and enjoy playing games, especially with their enemies, they get along excellently.
Katen is particularly close to Shunsui, expressing a great amount of concern when he is injured by the Quincy, Lille Barro. She has sworn an oath to remain with him until the very end, and even begs Shunsui to run away if his opponent is too strong — showing how important the Shinigami's life is to his Zanpakuto spirit.
5 Don't Get Along: Ashisogi Jizo And Mayuri Kurotsuchi
Ashisogi Jizo has one of the most frightening Bankai, transforming into a giant baby that exhales poisonous gas. However, the only way for it to have a good relationship with its master is to be completely subservient all the time.
Mayuri is the type of scientist who would not hesitate to modify the bodies of himself, his followers, and even his Bankai, conducting ruthless and often excruciating experiments on them. Due to Mayuri's vast intelligence and sadistic personality, there is no doubt that any form of resistance from Ashisogi Jizo is immediately and painfully crushed.
4 Get Along: Hisagomaru And Hanataro Yamada
Hisagomaru exhibits an introverted and apologetic personality, just like his master, Hanataro Yamada. Both of them prefer to get along with others as best as they can, explaining why they have such a good relationship.
It is clear that neither one of them has a violent bone in their bodies, as the Zanpakuto is actually incapable of doing damage to anyone in its initial Shikai state (a scalpel.) In this form, Hisagomaru prioritizes healing others — at the same time, the blade gathers energy from the wounds that it heals, which can then be concentrated into an incredibly powerful attack.
3 Don't Get Along: Ruri'iro Kujaku And Yumichika Ayasegawa
Ruri'iro Kujaku and Yumichika Ayasegawa would have gotten along much better if not for the fact that Yumichika rarely ever calls his Zanpakuto by his real name, instead calling him Fuji Kujaku.
Since Yumichika is part of Squad 11, which prides itself on immense physical strength, he is ashamed of his Shikai — given that its powers are kido-based, rather than melee. This rejection of his Zanpakuto's name is naturally insulting to Ruri'iro Kujaku, who consequently refuses to reveal his true power when released.
2 Get Along: Zabimaru And Renji Abarai
Zabimaru is one of the few Zanpakuto actually seen training with their Shinigami. Although Renji gains a Bankai in the Soul Society Rescue arc, it is initially an inferior version of his true Bankai. For a long time, Zabimaru doesn't fully acknowledge Renji as being worthy of wielding the entirety of the Zanpakuto's abilities.
This changes after Renji passes Oetsu Nimaiya's test, besting the foes he is pitted against, thereby proving that he is ready to handle his Bankai's power. Zabimaru only acknowledges Renji after he learns the real name of his Bankai: So-o Zabimaru.
1 Don't Get Along: Kazeshini And Shuhei Hisagi
Although more willing to use his Shikai than Yumichika, Hisagi freely expresses his displeasure with the shape of his Zanpakuto. He states that Kazeshini looks like something that solely exists to kill others.
While his Bankai is never revealed in the manga, Hisagi insists that he has learned it, meaning that he is able to establish communications with his Zanpakuto spirit. Further, Kazeshini behaves independently of his wielder, often going against Hisagi's directives in the Zanpakuto Unknown Tales arc.