Zanpakutō

A is the main weapon of the  Shinigami, the Arrancar and the  Vizard. The art of using a Zanpakutō is called.

Overview
Each Zanpakutō is a manifestation of its owner's soul, and has a unique name which is required for a shinigami to learn in order to use Shikai and Bankai. As such each Zanpakutō has unique abilities that match their owner's characteristics and personality, and their names usually hint to what these powers may be. A Zanpakutō spirit is part of its owner's soul, and often share the same personality traits. At the same time, they are also independent, and thus can be considered a Shinigami's partner in battle. Because they are part of their owner's soul, a Zanpakutō cannot be replaced, though it will slowly regenerate if broken. As a Shinigami gains power, their Zanpakutō can change form by allowing the inner being to manifest itself to a greater degree in the outside world. The sword and the inner being are synonymous to each other. No matter what form (or size) a Zanpakutō takes, it is always virtually effortless for its owner to wield because it is a part of its owner's soul. On the other hand, it is much more difficult for a Shinigami to wield a Zanpakutō that is not their own; Kaname Tōsen is the only known Shinigami so far to actually do such a thing. Most Zanpakutō look like regular katana, with slight variations between them as one would expect between different swords. Each Zanpakutō has the power to send pluses to the afterlife, purify Hollows, and transform the Zanpakutō itself into more elaborate and powerful forms. Not all Shinigami can hear the name of their Zanpakutō and thus can not achieve the higher tiers of power.

Forms
Depending upon the Shinigami's ability to communicate with and control their Zanpakutō's spirit, a Zanpakutō can manifest itself in two additional forms and revert to a sealed state. These two forms, known as Shikai and Bankai, are akin to "upgrades" for the Zanpakutō, giving it abilities far beyond that of its simple use as a sword. Shinigami usually carry their Zanpakutō in the sealed state and activate the released forms as necessary. Shinigami with Zanpakutō of the constant-release type, such as Ichigo Kurosaki, are unable to seal their Zanpakutō and therefore carry them in released form constantly.

In addition to the upgraded forms, the sealed form of a Zanpakutō can also be radically altered, though such alterations are purely cosmetic and usually don't offer any significant advantage in battle; one exception is Ikkaku Madarame's Hōzukimaru, whose hilt stores a blood-clotting ointment. Shinigami with great spiritual power and who are unable to control it have larger Zanpakutō, as Ichigo Kurosaki did when he first became a Shinigami. Isshin Kurosaki, Ichigo's father, explains at one point that high-level Shinigami must be capable of maintaining and suppressing the size of their sword. Otherwise, they would end up swinging around swords the size of skyscrapers. Zanpakutō can also be disguised as other objects, though such objects seem to need to be of similar proportions to the sword itself. Both Kisuke Urahara and General Yamamoto, for example, disguise their Zanpakutō as canes.

Shinigami who are unable to communicate with their Zanpakutō wield a nameless version known as "Asauchi".

Shikai
The is the second form (or first "upgraded" form) available to a Zanpakutō. To activate it, the Shinigami needs to learn the name of their Zanpakutō (one notable exception is Kenpachi Zaraki who was able to achieve Shikai without learning the name of his Zanpakutō). This is not as easy as simply picking a name, as the living spirit of the Zanpakutō already has its own name. Therefore, the Shinigami must be able to communicate with their Zanpakutō effectively, which requires being able to speak to the spirit within its world. Achievement of the Shikai is a mark of control of a Zanpakutō, and it appears to be a requirement for advancement within the Shinigami ranks, as most seated officers and presumably all Lieutenants are capable of Shikai. The one exception is Rukia Kuchiki, although she has the power of a seated officer, she is only not a seated officer on the request of her brother.

After first learning the Zanpakutō's name, the Shikai can be performed at will simply by speaking a command followed by the Zanpakutō's name. The commands vary between users and range from a simple imperative verb to a short poem. They often relate to the Zanpakutō's signature ability, or hint at the nature of its spirit. This step may be bypassed by expert Shinigami who have learned how to use their Bankai, although this has only been demonstrated once, by Renji Abarai. In rare cases, a Zanpakutō, once released, will remain in that state indefinitely. Such Zanpakutō is described as a full-time released form type, such as Ichigo's.

Once the Shikai is activated, the Zanpakutō will change form to access whatever special abilities it is capable of. They usually remain in the form of a sword (with multiple exceptions, such as Soifon wielding a stinger, Ikkaku Madarame wielding a spear, Kaien Shiba wielding a trident, Marechiyo Ōmaeda wielding a flail and Shūhei Hisagi wielding two connected dual scythes), but the type of sword differs radically among various Zanpakutō. The special abilities of the Zanpakutō, like the Zanpakutō itself, have specific names that usually must be announced to fully activate the effect. As Ichigo's Zanpakutō, Zangetsu, explains, knowing the name of an attack and not knowing it makes a difference in the amount of power that attack has.

Bankai
The is the third and final form of a Zanpakutō. To achieve it, one must be able to materialize their Zanpakutō's spirit in the real world and subjugate it, giving the Shinigami full reign over the Zanpakutō's power. According to Yoruichi Shihōin, the power of Bankai typically increases a Shinigami's power by a factor of ten. Because such an act usually takes hundreds of years of combat experience to achieve, it is rare amongst Shinigami and almost exclusively limited to the thirteen Shinigami Captains in the Gotei 13. Byakuya Kuchiki claims that among the four noble houses of Soul Society, only one person in several generations will be born with the spiritual power necessary to achieve it. Even with this, several years of special training are needed to achieve Bankai, plus the experience needed to master it. Ichigo Kurosaki and Kisuke Urahara are the only known individuals that have mastered Bankai through a far shorter, yet much more dangerous method. Using a special device created by Urahara, which forcibly materializes a Zanpakutō spirit (thus bypassing a large portion of the training), they were able to attain their Bankai within three days instead of the normal hundreds of years. After successfully testing the device and achieving Bankai, Urahara stated that training by using this method for more than three consecutive days could prove to be fatal, which is why Ichigo was also forced to achieve his own Bankai within three days. Besides Ichigo Kurosaki, the only non-Captain Shinigami known to have achieved Bankai are Renji Abarai (Lieutenant), who finalized his training at about the same time as Ichigo (although he did not use Urahara's device, but rather perfected it while Ichigo was training), and Ikkaku Madarame (3rd Seat), who did so through his own years of training.

After a Shinigami is able to materialize and subjugate their Zanpakutō's spirit, the Zanpakutō can assume its final and most powerful form. Unlike the Shikai, there is no command phrase to activate Bankai, though the user will usually say "Bankai" beforehand. A Zanpakutō's Bankai is often a manifestation of the spirit itself, usually creating a massive creature or a powerful effect to aid the user in battle (Ichigo's Bankai is an exception, becoming more compact instead). The Bankai itself will receive a different name in addition to the ordinary Zanpakutō (for example Ichigo's Zangetsu becomes Tensa Zangetsu, Byakuya's Senbonzakura becomes Senbonzakura Kageyoshi). Certain Shinigami also change with their Zanpakutō, gaining clothing similar to what their Zanpakutō's spirit form looks like. Most Zanpakutō will also gain additional special abilities, or a more enhanced version of the usual one. Like with the Shikai, most of these abilities have an associated name. Maintaining the Bankai is taxing for the wielder, and it is difficult to maintain it for long periods of time for most Shinigami, with the exception of Ichigo, as it becomes more compact, thus allowing him to hold it for long periods of time.

The power that comes with Bankai, takes from the shikai's ability/theme but amplifies it to many different levels of power. Some simply increase the original ability, such as Byakuya's blade count multiplied, or Sanjin who instead of only getting pieces of the giant, summoned the giant itself. While other Bankai follow the theme of the sword, such as Renji's remains a whip while containing baboon and cobra features, or Mayuri summons a monster with the same face (Jizo) on his trident, but kept the theme of poison that came from the monsters breathe.

So, once the Shikai's form and abilities are revealed, it is easy for fans to imagine/determine how/what the Bakai will be like.

Types
There are several types of Zanpakutō, classed by the main purpose or effect of their special abilities. These types include:


 * Melee-Type Zanpakutō: are typically designed for various forms of armed melee combat rather than magic-based abilities.


 * Ichigo Kurosaki/Hollow Ichigo
 * Kenpachi Zaraki
 * Renji Abarai
 * Ikkaku Madarame
 * Makoto Kifune
 * Shuhei Hisagi
 * Marechiyo Omaeda
 * Sajin Komamura


 * Kidō-Type Zanpakutō: are designed around a special ability rather than close combat potential.


 * Yumichika Ayasegawa
 * Momo Hinamori
 * Sōsuke Aizen originally claims his is a "flowing-water-type Zanpakutō," but this is later proven to be a lie.
 * Retsu Unohana
 * Kisuke Urahara
 * Kaname Tōsen
 * Hanatarō Yamada


 * Projectile-Type Zanpakutō: when released separate into many air based blades/substance-based projectile that the owner can control freely.


 * Jirōbō Ikkanzaka
 * Byakuya Kuchiki
 * Rangiku Matsumoto


 * Defense-Type Zanpakutō: are designed around defensive capability with little or no offense.


 * Rusaburō Enkōgawa

A large amount of the Zanpakutō are classified by elements, generally utilizing their respective elements as forms of attack. (It could be said that elemental Zanpakutō are all Kidō-Type which have an element based as noted by Kenpachi Zaraki and Maki Ichinose during their battle, but as this was only mentioned in the anime Episode 98 it cannot be stated as fact.)


 * Fire-Type Zanpakutō: designed to manipulate fire for various forms of attack.


 * Shigekuni Yamamoto-Genryūsai
 * Shūsuke Amagai


 * Ice-Type Zanpakutō: designed to manipulate ice for various forms of attack.


 * Tōshirō Hitsugaya / Sōjirō Kusaka
 * Rukia Kuchiki
 * Isane Kotetsu


 * Wind-Type Zanpakutō: designed to manipulate wind for various forms of attack.


 * Shunsui Kyōraku
 * Kensei Muguruma
 * Senna


 * Water-Type Zanpakutō: designed to manipulate water for various forms of attack.


 * Kaien Shiba / Aaroniero Arruruerie (taken from Kaien Shiba)


 * Water/Electricity-Type Zanpakutō


 * Jūshirō Ukitake


 * Plant-Type Zanpakutō: designed for the manipulation of plant growth for offense or defense.


 * Ryūsei Kenzaki


 * Light-Type Zanpakutō: designed to manipulate light for various forms of attack.


 * Maki Ichinose


 * Poison-Type Zanpakutō: designed to administer poison as a form of attack.


 * Soifon
 * Mayuri Kurotsuchi

Unknown (These are the Zanpakutō whose types have not been stated but we do know their name and at least the Shikai for each.)


 * Gin Ichimaru
 * Izuru Kira
 * Chōjirō Sasakibe

Sub-Types
There are a few "sub-types" of Zanpakutō classification such as:


 * Constant-Release Type: this group pertains to Zanpakutō whose wielders are unable to revert them back to their default sealed states after initiating the Shikai release. Such a phenomenon is mainly due to the vast spiritual power of the sword's wielder, such that they are unable to completely seal their Zanpakutō like other Shinigami.
 * Kenpachi Zaraki
 * Ichigo Kurosaki


 * Dual-Blade Type: this group pertains to Zanpakutō that feature more than one bladed weapon in Shikai release. It is decidedly rare for one to possess such a weapon and therefore it says a lot about its wielders spiritual power uniqueness.


 * Jūshirō Ukitake
 * Shunsui Kyōraku
 * Shūhei Hisagi