Shinigami

are a race of spiritual beings that act as enforcers and psychopomps who all share similar supernatural powers. They are souls with a high level of innate Spiritual Energy, recruited from the ranks of the residents and nobility of Soul Society. Like all spirits, they cannot be detected by normal humans. Shinigami use their Zanpakutō, supernatural swords that are the manifestation of their owners' power, to perform soul burials on Pluses. Shinigami also use their Zanpakutō as well as magic known as Kidō to fight their archenemies, the Hollows.

Overview
Shinigami are souls that have supernatural powers. As such, their bodies are composed of Spiritrons (spirit particles) instead of atoms. This means that just like most other types of spirits, they can only be seen by other spiritually aware entities, which excludes most humans. Nevertheless, they are quite capable of influencing their environment. Shinigami are the personification of death. Their job is to send spirits to Soul Society (the afterlife) in order to maintain a balance of souls between it and the material world, and to exorcise evil spirits. They all have katana known as Zanpakutō, though not all of them carry them. Additionally, they can be injured and die like regular humans, though it takes considerably greater injuries for the latter to occur than it would in regular humans. There are a few runaway Shinigami, namely Yoruichi Shihōin and Kisuke Urahara. Ichigo Kurosaki is what is known as a Substitute Shinigami, which is a Shinigami who gained powers by taking another's. At first, he uses Rukia Kuchiki's powers which he lost during a fight with Byakuya Kuchiki. In order to defeat him, he had to gain his own Shinigami powers, which he did by a very dangerous process that almost killed him. This process turned him into what is called a "Vizard." These are Shinigami who have gained Hollow abilities, and use them to gain power far exceeding and beyond that of a normal Shinigami or a normal Hollow.

Additionally, unlike humans, they do not have to eat anything to sustain themselves. Shinigami and other spiritual beings only become hungry when they used too much Spiritual Energy within a short amount of time.

The most prominent supernatural power possessed by a Shinigami is their Zanpakutō, a supernatural sword generated from the Shinigami's soul. Shinigami also naturally give off Spiritual Energy, which varies greatly in magnitude with the strength of a Shinigami. A Zanpakutō is a physical manifestation of this force concentrated into a blade.

Shinigami operations are based out of Soul Society, where departed human souls reside. Travel between the human world and Soul Society is extremely limited and monitored, but some Shinigami are stationed in the human world to carry out their duties and therefore must often travel between the two. In addition, it is a crime for a Shinigami to remain in the human world longer than a certain time limit as this is viewed as living a second life.

It is also implied that Shinigami receive salaries, like workers in the real world.

Appearance
Most Shinigami appear like Humans, a notable difference being their mostly old-fashioned garments by 20th-21th century standards (see uniforms at Gotei 13 and at Onmitsukidō), and their Zanpakutō which is in most cases tied to their obi sash.

There are, however, a few Shinigami who are less Human-like in appearance. For example it seems that between Shinigami there are much greater variations in body-sizes than between Humans, as there are real giant-like entities (e. g. the four guards of the four gates to Seireitei) and also ones with extremely small stature among them (e. g. Yachiru Kusajishi). This variation seems to occur not just between Shinigami, but also between regular dwellers of Soul Society, too.

Variations do not just occur in size but in overall appearance, too, the most notable example being Captain Sajin Komamura, who appears like an anthropomorphic canine.

Duties
A Shinigami's duties include leading Pluses (ghosts) to Soul Society in a practice called, and the cleansing of Hollows (evil spirits). Later in the series, Shinigami duties are clarified further, and it is revealed that they are also responsible for governing the flow of spirits between the human world and Soul Society.

Training
The majority of training for individuals (that is, souls residing in Soul Society) wanting to become Shinigami is done through the Shinigami Academy. It is a six-year academy, during which time its students learn how to use their Spiritual Energy properly, fight Hollows, and perform Soul Burials. While the exact date and details of its foundation are not specified, the academy seems to have been founded by Shigekuni Yamamoto-Genryūsai about 2000 years before the Bleach storyline.

Not much is known about the conditions on which a dweller of Soul Society is admitted to the Academy. One elementary requirement seems to be that the individual has to possess a certain, above-average level of Spiritual Energy, and has to be able to perform some basic feats using that. Becoming hungry seems to be a good sign in Soul Society for hopeful Shinigami candidates, because feeling hunger means that the person in question is capable of using up Spiritual Energy.

Combat
The cleansing of Hollows is very dangerous task, as most Hollows are no more than mindless monsters thirsty for devouring more and more souls, be it a Plus, a Human soul still in its body, or a Shinigami. Moreover, Hollows who have some of their human consciousness remaining are even more dangerous, as they can be swift, strong and cunning adversaries, utilizing various tricks to avoid purification and catch their prey.

Taking these facts into consideration, Shinigami have to be highly trained in defending themselves and other spirits from being devoured, while being able to land a critical strike on the Hollow itself with their Zanpakutō.

Shinigami have four skills utilized in combat: Kidō, hand-to-hand combat, superhuman agility (footwork), and swordsmanship, all of which require the controlled usage of a varying amount of Spirit Energy.

Kidō
Kidō are a type of sorcery used by Shinigami. They can be used for various purposes, such as healing, attacking, and restraining. Healing seems to be a more general skill, while attacking and binding require an incantation to be recited beforehand. Demon arts spells are divided into two major groups: destructive spells, used for direct attack, and binding spells, which are spells that restrain someone or have other effects. These forms of demon arts spells are performed by calling out a complicated and often long-winded incantation followed by the name of the spell, which causes an effect once the name has been recited. Lesser versions of the spells can be used by calling out the name alone, but their effectiveness is reduced when used in such a fashion.

Hand-to-hand combat
Hand-to-hand combat is not elaborated upon by the majority of Shinigami. The Onmitsukidō troops, however, especially those of higher ranks such as Soifon, are known to be well-trained in this field.

Agility
Hohō (agility), like hand-to-hand combat, is not elaborated upon by every Shinigami. Flash steps (Shunpo), a movement technique that allows the user to move faster than the eye can follow, is implied to be part of this category, and most (though not all) Shinigami are able to perform it to some degree. Another skill, though not necessarily related, is the ability of some Shinigami to walk on air using spiritual power. By collecting and solidifying spiritual particles beneath their feet, Shinigami can gain traction on thin air to either freely move about or to stop themselves from falling.

Swordsmanship
is the most used form of combat among Shinigami, since their Zanpakutō is the most effective way of dispatching any given opponent. As the name suggests, it involves using a Zanpakutō and its various special abilities to attack an opponent. In addition to its basic form, each Zanpakutō has two enhanced forms: shikai ("initial release") and bankai ("final release"), which change the sword's form to unlock its potential and that of its user.

Mission aids
To aid in their missions, particularly when said missions involve more than simply dispatching a Hollow, Shinigami have a number of unique items to assist them in their duties. In addition, it should be noted that all Shinigami captains and lieutenants have their spiritual energy reduced by about 80% when they enter the human world by use of a spiritual limit, represented by a seal resembling the symbol unique to their division, in order not to cause unnecessary damage while there. In extreme cases where their full power is needed, they can request a limit release.

"Skull Symbol"
Though not officially named, it seems to be an important tool for Shinigami during missions in the real world. It can basically force out one's spirit from a human body or a gigai (see below), a human soul or an artificial one alike (see also below). Rukia Kuchiki has a glove which has this skull symbol on it, and she uses this glove several times to force Ichigo out of his body. Kisuke Urahara also has a skull symbol on the end of his cane, which can be used in the same manner. The skull also appears on Ichigo's seal of approval. They always touch Ichigo's forehead with the symbol, it is unknown if pressing the symbol against other body parts has the same effect or not(Uryū Ishida uses Ichigo's license to remove Nova's soul by striking it on his thigh, it seems poking the forehead is only done for dramatic reasons).

Hell Butterfly
are completely black butterflies that serve various purposes. They guide the Shinigami through the Senkaimon when travelling between Soul Society and the Human World, thereby saving them from the inconvenience of passing through dangai. Hell Butterflies are also used as messengers between Shinigami, often carrying important orders. It is implied that Hell Butterflies are bred and taken care of by Shinigami in Seireitei, the latter task being carried out usually by new and inexperienced members of the Gotei 13. Hell Butterflies, like the Shinigami themselves, are only visible to spiritually aware beings.

Gigai
In certain circumstances, a Shinigami will need a way to stay in the human world for long periods of time, interact with the living, and/or recover their powers when the need arises, all of which they can't do in spirit form. Thus, the gigai was developed.

Artificial souls
Artificial souls, as the name suggests, are souls designed by Shinigami scientists to separate a Shinigami's spirit from a Gigai, should they be inhabiting one, or to evict stubborn spirits from their corpses if necessary. It is commonly called Soul Candy, as the Shinigami Women's Association complained that the name "Artificial Soul" (Gikongan) was not cute and had it changed.

Modified souls
are artificial souls designed to enhance regular human physiology, making them capable of battling Hollows equally. The modsouls are condensed into tiny, candy-like orbs and placed into corpses to achieve their function as soldiers to combat Hollows. They are also more independent to fit with their purpose. The modsouls were exterminated after the experiment was halted due to ethical reasons, since they were intended to be used to reanimate human corpses to use as weapons against the Hollows. But there are still a small amount left; namely Kon, Ririn, Kurōdo, and Noba.

Memory replacement
In some cases, a human witnesses a Shinigami purify a Hollow or affect his surroundings in a significant way. To keep the incident a secret, Shinigami perform memory replacement with an item called kikanshinki (記換神機). When used, a bird's head pops from the top of the device and produces a puff of smoke. The human it is used on is knocked unconscious and wakes up a while later with a new memory. However, the new memory that the human acquires is random and often based on the limits of what they themselves will believe. For example, Ichigo's family merely believed they slept through a truck crashing into their house when it was used on them. Conversely, Orihime Inoue, who has a much more active imagination, believed that her house was attacked by a Yakuza gunman.

Soul phone
A vital tool for any Shinigami stationed in the real world, this variation on a cell phone functions both as a regular phone and as a communication line with Soul Society. It receives information about the time and exact location of a Hollow's emergence via a Global Positioning System (GPS). A Shinigami's kills are also recorded in the phone and can be used as currency (according to the bounty placed on each Hollow).

Substitute Shinigami
A Substitute Shinigami is someone who became Shinigami by obtaining another Shinigami's power, or by going through a much harder and riskier process to transform him/herself into one. Obtaining another Shinigami's power is done by thrusting his/her Zanpakutō into the person's chest who wants to obtain the power. However, the percentage of success is low. In the case of success, the person normally obtains around half of the Shinigami's power, and only temporarily. In Ichigo Kurosaki's case however, the whole power of the original Shinigami, Rukia Kuchiki was transferred into him, due to his enormous innate spiritual power.

This practice is forbidden by Soul Society, as it can give birth to rogue Shinigami with great power, thereby it is only applied as a last resort measure.

In the case the individual borrowing the power being a Human, several difficulties arise, illustrated by the example of Ichigo. In order to be able to fight as a Shinigami, he has to leave his body and get into soul state, which can only be done if he is "killed" (at least put into clinical death) by the "skull symbol" of another Shinigami, or if he swallows a Soul Candy, forcing his soul out of his body. In the former case, his body needs to be taken care of until he finishes his job and re-enters it.

The other method of becoming a Shinigami is even riskier, and is only possible for individuals with spiritual power well above the average level. The only example so far is Ichigo Kurosaki. In the first step, his soul was forced out of his body and his Chain of Fate was cut. In the next step, he had to get accustomed to controlling his spiritual body confidently. In the third step, he was forced into a situation from where he can only escape by using Spiritual Energy. To be able to use it, he had to communicate with the spirit of his own Zanpakutō, who has been lying dormant in the depth of his soul up to this point, and find his own Spirit Thread. Had he not succeeded in his step, he would turn into a Hollow. Finally, he had to learn the name of his Zanpakutō and call it out, releasing its Shikai.

Despite the above-mentioned difficulties, there are known examples of succesful and valuable Substitute Shinigami, as mentioned by captain Jūshirō Ukitake. These Shinigami, including Ichigo after the Ryoka Invasion of Soul Society, receive a badge called the Seal of Approval. This item serves several functions. One is to identify the owner in the case he/she meets other Shinigami, another is to indicate if Hollows are nearby via an alarm sound. The latter can only be heard by the owner, and the item itself is only visible to other spiritually aware beings, allowing the owner to keep it with him/herself all day long without attracting unwanted attention. The Seal of Approval can also fulfill the functions of the Shinigami "skull symbol", being able of forcing out spirits out of their bodies, which comes in handy in the case of a Hollow attack, when the Substitute Shinigami has to leave his/her body immediately. The Seal of Approval has a skull symbol similar to, but not identical to the one carried by regular Shinigami engraved on it.

Vizard
Vizards are a group of rogue Shinigami who have been banished from Soul Society for illegally obtaining Hollow powers.