Zanpakutō

Basics

Zanpakutō are one of the few types of weapons able to cut spiritual bodies, which makes them an effective tool in combating Hollows. Every Shinigami carries a Zanpakutō, and each is unique to its wielder, born from their souls. Zanpakutō have a physical form, but the 'soul' of the weapon is a sentient being that is a separate entity from its wielder, with their own spiritual pressure, and the the spirits' names apply to both the weapon and the spirit itself. The spirits reside in a Shinigami's inner world, though they can manifest outside- often only their wielder can see them when that happens. Zanpakutō spirits come in many different forms with many different personalities, and can even have a poor relationship with their wielder. Often, however, wielders and their Zanpakutō have a close bond, and Shinigami can visit their inner worlds to train via meditation. Zanpakutō can also forcibly pull their wielders into their inner world when needed.

A Zanpakutō's physical form and powers are based on the wielder's soul, and can be changed throughout a Shinigami's life. Zanpakutō spirits are born with their wielders, and die only when their wielder does. Though a Zanpakutō spirit is its own entity, Shinigami and their Zanpakutō are one with each other.

Types

Asauchi

Though it is possible for a Shinigami to manifest a Zanpakutō on their own, it is highly difficult and rare. Instead, most Shinigami use a focus in the form of empty Zanpakutō known as Asauchi (浅打ち, Shallow Hit). These spriit-less blades allow a Shinigami to focus their Reiyoku to form their true Zanpakutō and communicate with the spirit in order to learn its name. Without knowing the Zanpakutō's name, a Shinigami can only use an Asauchi as a simple blade. After learning a Zanpakutō's name, a Shinigami can unlock the weapon's first release, known as Shikai. With proper training, a final release known as Bankai can be obtained.

Asuachi were invented by Oda Makoto during the First Shingiami Civil War, which is why most Zanpakuto appear as katanas or other Japanese blades- the first Asauchi-born Zanpakutō were all katanas in their sealed states. Prior to Makoto, Shinigami fought with their bare hands, or primitive Zanpakutō-precursors forged by pumping one's reiatsu into a regular weapon. It is known that the founders of the Gotei 10, the Saisho no Gādian had weapons akin to Zanpakutō.

All Asauchi are standard-issue, with variations only in handle and blade length. All have brown handle wrappings, grey, circular tsuba, and brown sheathes. Academy students are given their Asauchi in the middle of their second year.

Arrancar Zanpakutō

After the Second Aspect treaty, the Aspects promised to remove themselves from human affairs. However, many Aspects were concerned that Shinigami couldn't handle keeping the balance of souls without help. With approval from Death, many Aspects began choosing and attaching themselves to human souls, replacing the part of the soul that would have formed a regular Zanpakutō spirit.

An Aspect Zanpakutō functions identically to a regular one, and most Shinigami with an Aspect are unaware of the fact. Aspects cannot reveal themselves to a Shinigami unless under dire circumstances, in which they can then reveal what they are and offer a contract to help their Shinigami. These contracts further bond a Shinigami and the Aspect spirit, and the Shinigami is granted advanced powers- with a cost, and a punishment if the cost is not met.

Zanpakutō Facts

• All Asauchi are forged by the Oda Clan, and no one outside the clan knows the secret to making them. All Asauchi bear the Oda Clan mon on their habiki, though most Shinigami chose to conceal the mon when they learn their Zanpakutō's name.
• A Zanpakutō cannot be replaced. However, they can be repaired by their wielder, and will slowly regenerate based on the wielder's health and reiatsu. A Zanpakutō can be destroyed without killing the wielder, however a Zanpakutō will always die if their wielder does. The only cases this is not true is with an Aspect Zanpakutō. 
• Many Shinigami choose to keep their Zanpakutō's sealed form as a katana, due to having leaned to wield it in that form in the Academy. However, some Shinigami choose to alter the sealed form to weapons they are more familiar with. Some, like Captain Kelzang Dorje, seal their Zanpakutō as more mundane objects, like a necklace. 
• The theory that a Zanpakutō's size reflects its user's spiritual pressure is inaccurate. The control a user has over their Zanpakutō's spiritual pressure is a reflection of their power- skilled users can fully contain and conceal the spiritual pressure, while novices cannot. 
• A Zanpakutō has its own unique Reiatsu, which can be felt along with its wielder's. 
• Zanpakutō can decide whether or not their wielder is worthy of using their powers, and no Shinigami can force their Zanpakutō into granting their powers by force. Some Shinigami never learn their Zanpakutō's name.
• A Shinigami can fall out of harmony with their Zanpakutō, and can even lose the ability to perform Shikai or Bankai. 
• There is no Zanpakutō in existence that has a Shikai and Bankai that are unrelated in power.
• Elemental Zanpakutō can only use attacks of their element. Likewise, a melee-type Zanpakutō cannot be used to channel Kidō, ect.
• A Zanpakutō's name is typically in the language of its wielder's dominant race.
• The 12th Division keeps a record of all Zanpakutō and the names of their forms. For consistency's sake, the names are recorded in their native language, and translated into Japanese.

Powers

General Powers

The general powers of a Zanpakutō can be accessed even by those who only wield an Asauichi.

• Konsō (魂葬, Soul Burial) is the way Shinigami send Pluses to the afterlife- good souls to Soul Society, and unredeemable souls to Hell. Konsō is traditionally performed by tapping a plus's forehead with the pommel of a Zanpakutō
• Hollow Purification: A Shinigami can cleanse a Hollow by slicing its mask, which returns it to being a plus and sends it along to either Soul Society, if it started its Hollow life in the World of the Living, or reincarnate its soul back into the Human World, if it began its Hollow life in Soul Society. Hollows that were evil as humans or Pluses are sent to Hell.
• Soul Cutting: The ability to cut beings made of Reiyoku, as well as living beings.

Forms 

• Sealed: Once a Shinigami has learned their Zanpakutō's name, they gain the ability to customize their standard-issue Asauchi as they see fit, limited only by the Shinigami's own Spiritual Pressure. A Zanpakutō will often choose its initial sealed form, and the Shinigami is then allowed to change it if they wish. Most Zanpakutō and Shinigami choose to leave their sealed forms as regular katana, customizing only the colors and length of the blade.

• Shikai (始解, Initial Release): The second form of a Zanpakutō, obtainable once a Shinigami has learned their Zanpakutō's name, and have visited their inner world to harmonize with their Zanpakutō. This is also where they learn their release command, which are as unique as the Zanpakutō themselves. All commands relate to the Zanpakutō's form or powers.

• Bankai (卍解, Final Release): The second, and widely considered final form of a Zanpakutō. To achieve Bankai, a Shinigami must learn to enter their inner world without help, then be able to pull their Zanpakutō's spirit into the physical world and defeat it in combat. This is incredibly difficult, and takes on average ten years to achieve. Many Shinigami start with sparring with their Zanpakutō in their inner world.

A newly achieved Bankai is almost always incomplete- many Bankai have hidden forms and abilities that can only be obtained through further training. Generally, even an incomplete Bankai increases the user's strength 5-10 fold, which is why Bankai is considered a Zanpakutō's ultimate form. Some Zanpakutō purposely withhold a Bankai's true form from their Shinigami until they feel the Shinigami is ready for it.

Bankai are dangerous because of the immense power they hold, and most Shinigami are cautioned to never use it unless absolutely necessary- a Bankai can hurt a wielder as much as their opponent, and can cause incredible collateral damage. On top of that, a broken Bankai can never be repaired to its former strength and form.

All captains are required to know their Bankai, and captain-commanders and Royal Guard members can only be appointed if the candidate has mastered their Bankai.

• Reikonkai (霊魂解, Soul Release): A form, often considered to be a form of Bankai, in which a Zanpakutō lends so much of its power to their Shinigami that the Shinigami takes on physical traits of their Zanpakutō. This form is very rare, and only seen when a Zanpakutō and a Shinigami are in total harmony. Contracted Shinigami are known to have an easier time attaining this form, however it is so rare many believe Reikonkai to be a myth. Hattori Fuu's true Bankai was once considered a Reikonkai, however that is a highly debated fact.
  

Classifications

Melee