The Zanpakuto of low-ranking Shinigami are called Asauchi and do not have names, but the Zanpakutō of Shinigami of rank have names. In its sealed state, a Zanpakutō has the form of a Japanese sword. Such weapons are unique swords generated from their owner's souls. Its shape differs depending on its owner.
Zanpakuto are the trademark weapons of the Shinigami. Capable of cutting spiritual bodies, they are among the few weapons which can be used to combat Hollows. Each Shinigami carries a Zanpakuto, and each Zanpakutō is unique: the swords are reflections of a Shinigami's power and soul, and sentient beings unto themselves. The Zanpakutō's name is the name of the living spirit which empowers the sword and lends its strength to the Shinigami who wields it. These beings can vary greatly in appearance, and have their own distinct personalities, which match their owner's.
A Zanpakuto's shape and abilities are based on their Shinigami's soul. Once a Shinigami learns his/her sword's name, they can communicate with one another and grow stronger together. Zanpakuto are born with their Shinigami, and they die along with their Shinigami. Shinigami use them in battle as a reflection of their heart. When released, they can display a vibrant power. They are one with the Shinigami, and they share a Shinigami's conviction.
Inside each Zanpakuto is an incarnation which manifests itself upon the Zanpakuto's transformation. The first step is to acquaint oneself with this incarnation.
Obtaining A Zanpakuto
Depending upon the Shinigami's ability to communicate with and control their Zanpakuto's spirit, a Zanpakuto 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 Zanpakuto, giving it abilities far beyond those of its simple use as a sword. Shinigami usually carry their Zanpakuto in its sealed state, and activate the released forms as necessary.
A Zanpakuto can change size and shape depending on the spiritual strength of the owner.
All Zanpakuto have two levels of release. The first one is Shikai and the second one is Bankai. One must be able to perform both of them to become a captain. The power and forms of Shikai and Bankai are dependent on the Zanpakutō, and vary according to the wielder's strength and training.
Most Zanpakuto look like regular katana, with slight variations between them as one would expect between different swords. Their variations are commonly:
- Katana - The term katana may be applied to the standard-size, moderately curved, Japanese sword with a blade length of greater than 60 cm (23.6 inches). The katana is characterized by its distinctive appearance: a curved, slender, single-edged blade, a circular or squared guard, and a hilt long enough to accommodate two hands.
- Wakizashi (Side Insertion) - A short blade between 30 and 60 cm (12 and 24 inches), with an average of 50 cm (20 inches). It is similar to but shorter than a katana, and usually shorter than the kodachi. The wakizashi was usually worn together with the katana. When worn together, the pair of swords were called daisho (large and small). The katana was often called the long sword, and the wakizashi the companion sword.
- Nodachi (Field Sword) - The nodachi was more difficult to wield due to its size and weight. The length of the hilt of the nodachi varied between twelve to thirteen inches (30 to 33 centimeters). Due to its weight and size, its cutting capability and range exceeds those of a katana.
- Kodachi (Small Sword) - The kodachi is type of sword that are in the shape of a tachi and are mounted in tachi style but with a length of less than 60 cm (24 inches).
- Tanto (Short Sword) - The tanto is commonly referred to as a knife or dagger. The blade is single or double edged, with a length between 15 and 30 cm (6-12 inches, in Japanese 1 shaku). The tanto was designed primarily as a stabbing weapon, but the edge can be used for slashing as well.
Shikai (Initial Release) is the second (or first upgraded) form available to a Zanpakuto. To activate it, the Shinigami needs to learn the name of their Zanpakuto. This is not as easy as simply picking a name, for the living spirit of the Zanpakuto already has its own name. The Shinigami must be able to communicate and harmonize with their Zanpakuto effectively, which requires being able to speak to the spirit within its world.
The blade changes shape and gains special abilities by chanting a Kaigo (Release Call), or release incantation. Using the Kaigo, followed by the name of the Zanpakuto, activates Shikai. It is crucial to memorize each phrase, for every Zanpakuto has a different incantation.
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. Occasionally, Shinigami who did not learn Bankai can release their Zanpakutō simply by saying its name.
Achievement of the Shikai is a mark of control of a Zanpakuto, and it is a requirement for advancement within the Shinigami ranks, for most seated officers are capable of Shikai. It is required in order to achieve the rank of lieutenant, for it is a requirement which most captains look for.
Bankai (Final Release) is the second and final upgraded form of a Zanpakuto. To achieve Bankai, one must be able to materialize and subjugate their Zanpakuto spirit. Materialization means the opposite of getting dragged into the Zanpakuto's inner world: the wielder needs to summon the Zanpakuto's spirit into the physical world. It usually takes 10 years or more to achieve, plus the experience needed to master it.
The power and forms of Shikai and Bankai are dependent on the Zanpakuto, and vary according to the wielder's strength and training. But in general, one's power can grow 5 to 10 times greater by attaining it. Only the strongest Shinigami can use it, and it is the ultimate technique of a Zanpakuto. Even the four noble families, whose members are always exceptionally talented, only have a member capable of Bankai every few generations. Those who achieve Bankai always have remarkable roles in the history of Soul Society.
Ichigo Kurosaki and Kisuke Urahara are the only known individuals who have attained Bankai through a far shorter, yet much more dangerous method. Using a special device created by Urahara, which forcibly materializes a Zanpakuto spirit (thus bypassing a large portion of the training), they attained their Bankai within three days instead of the normal hundreds of years. After successfully testing the device and achieving Bankai, Urahara stated training by using this method for more than three consecutive days could prove to be fatal, which is why Ichigo was forced to achieve his own Bankai within three days.
Weakness: The biggest flaw of Bankai lies in the overwhelming power it releases. Its power and form are often far beyond those of a normal weapon, which is why one needs to train at least 10 years with Bankai in order for one to become capable of using it completely and effectively. No Bankai should be used in battle before this period of time has been reached. A broken Bankai can never be returned to its former state. The only exception to this is Captain Sajin Komamura's Bankai: he and his Bankai share a bond so strong, when one is injured, the other reflects the damage, but the Bankai is healed when the captain is healed. A Bankai's form and strength is determinant on how much the spirit recognizes its wielder. If the Zanpakuto does not fully recognize its wielder, then it may not give its Bankai's true name. The result is the Bankai not being in its true form and therefore weaker.