Gotei 13

The Gotei 13 is the primary military branch of Soul Society and the main military organization most Shinigami join after leaving the academy.

The Gotei 13 were once a band of ruthless killers that were hired by the Central 46 for protection. The original 13 captains included Yachiru Unohana, Genryusai Yamamoto, Harotaissen Tsuribakki and 10 other criminals. After a while, they developed a sense of justice for the Sereitei, and settled down to be military captains instead of hired killers.

The Gotei 13 serves as a military force with its primary responsibilities consisting of: The Gotei 13 does not normally operate as a cohesive unit. The command of the divisions are generally left to the discretion of its particular Captain, who commonly runs it whatever way he or she sees fit, allowing for the change of a division's traditional duties to an entirely new set and even the creation of a separate institution connected to the division. The Gotei 13's main duty is to defend the Seireitei, but they are allocated districts in Rukongai to defend. In addition to these duties, Shinigami have to deal with the business of being assigned to the Human World.
 * The defense of the Seireitei, the center of Soul Society.
 * The deployment of Division members into enemy territory for combat operations.
 * The deployment of Task Forces as defensive measures in the Human World.
 * The guiding of souls to Soul Society.

The only general authority to call forth a combined front is an edict from the Central 46 Chambers, or more often the Captain-Commander. It is not uncommon for captains to not see each other as a whole group for long periods of time, except for cases involving a threat to all of Soul Society, a captain's punishment, or, to a lesser degree, a captain's promotion. On a regular basis, the captains are spread out all across Soul Society doing their divisions' duties, whatever they may be. They are so far spread out, getting the captains together as a group, or even getting their lieutenants together as a group, could normally take a day to accomplish.

Unless specifically ordered by the Captain-Commander, captains can choose whether or not to attend meetings (at their own risk) or not even involve themselves in the daily situations of Soul Society. Captains are not allowed, without permission, to carry out activities outside of their normal jurisdiction or their division. The captain of one division cannot punish the subordinates of another captain.

Officially, the Kidō Corps and Onmitsukidō are not part of the Gotei 13.

Structure
The Gotei 13 is made up of thirteen divisions, with several divisions having certain specializations.

The Gotei 13 is led by the Captain-Commander, who has the statuary authority to conduct all the affairs of the Gotei 13 while deferring to the authority of the Central 46 Chambers in matters involving Soul Society.

As with any army, the Gotei 13 has ranks. There are 20 ranks for officers, but no ranks for non-officers. The lower the number is, the higher the rank. The ranks and their descriptions are below, from highest to lowest in terms of strength. The Gotei 13 is an organization with a merit-based hierarchy. It has disposed of the system of rank based on seniority. Abilities are the only thing used to determine one's rank.

Captain's Council
The captains congregate in the main hall of the First Division Headquarters to discuss important issues involving their specific divisions and matters which affect Soul Society. This council is highly formal, with the captain-commander leading its proceedings. All captains are considered equal (with the exception of the captain-commander), and determine the course of their individual division unless dictated otherwise by the captain-commander. Votes are carried out via a unanimous consensus.
 * The Captain-Commander is the supreme leader of the Gotei 13. The position requires the Captain-Commander to oversee the overall operations of the Gotei 13, Onmitsukidō and Kidō Corps when the well-being of Seireitei and Soul Society is at stake. The only power the Captain-Commander answers to is the Central 46 Chambers, who elect the successor of the current Captain-Commander in the event of their death.

Captains are generally the most respected Shinigami within the Soul Society, with the leaders of the Kidō Corps and Onmitsukidō possibly being of equal status. Initially with one exception, all captains are able to utilize the final stage of their Zanpakutō, and are far more powerful than even their lieutenants. Knowing Bankai gives captains an average of five-to-ten times the strength of Shinigami who are unable to perform it. They have extensively trained, if not mastered, their Bankai, allowing them to use the enormous power effectively in battle. Most captains are skilled in the use of Shunpo and Kidō, and generally have extensive knowledge of Shinigami history and battle tactics. All of these factors create a vast power gap between captains and lower-ranked officers.
 * A Captain is the leader of one of the thirteen divisions (with the special case of the Captain-Commander).

They function as chief executive officers, and they determine the course, organization, tactics, and policy of their division. The power a captain has over his/her division is absolute and cannot be questioned by subordinates or the captains of the other divisions. A captain can choose to change the division specialty. Due to captains having supreme authority in their respective division, the divisions are separate entities and not a cohesive military. In this way, they only have the right to punish the actions of their subordinates and not those of other divisions unless the division in question has no current captain or the subordinate's actions are against the laws or rules of Soul Society.

The true power of Soul Society lies in the captains of the Gotei 13, as they are the leaders of its military arm. With them at full strength, Soul Society is safe and almost unbeatable. If they are broken, their strength dwindles, making them highly vulnerable.

There are three different ways to become a Gotei 13 captain:
 * 1) Captain Proficiency Test: A test which requires the ability to perform Bankai. Nearly all Shinigami become captains using this method. At least three existing captains, including the Captain-Commander, have to witness the test.
 * 2) Personal Recommendation: To have personal recommendations from at least six captains and approval from at least three of the remaining seven.
 * 3) Trial by Combat: To defeat a captain in one-on-one combat with at least 200 witnesses from the captain's division. This method is seen as being the exceedingly rarest and the least refined of the three. The method is commonly looked down upon by some captains as barbaric compared to the other refined methods. This method allows one to bypass having the mastery of Bankai or other possible abilities which a captain would otherwise be required to have knowledge of, for it allows no judgment from captains who would require those skills as a prerequisite to join their ranks. Though rare in other Divisions, the Eleventh Division has been set up to exclusively utilize this method, with each captain attaining their rank by killing the predecessor.

Lieutenant
Lieutenants function as executive officers for their division, taking care of or supervising day-to-day operations. Along with their captains, they are not assigned to one specific squad. They generally only know the Shikai of their Zanpakutō but they are still the second strongest in their division. In the case of a division captain's death, departure, or other circumstances making them unable to perform their duties, the lieutenant acts as the "substitute captain" until another can be assigned.
 * A Lieutenant; vice-unit commander, often translated as vice-captain) is the 2nd seated officer in a division.[13]

The authority to appoint or dismiss a lieutenant lies solely with the captain of the respective division, a privilege which was granted to them with the support of the Central 46 Chambers. Captains reserve the right to appoint multiple lieutenants at a single time, though this is rarely done due to it being both considered highly unorthodox and heavily frowned upon by the Central 46 Chambers. Though rarely exercised, any potential candidate retains the right to decline the nomination.

Seated Officers
Seated officers are the remainder of the officers in the Gotei 13 which hold ranks at or below 3rd Seat. Captains and lieutenants have the ranks of 1st and 2nd Seats, respectively. Next to that, there are 18 more seats (3rd-20th). In the Gotei 13, only one person can hold a senior officer rank (such as 3rd or 5th seat), but there are several holders of junior officer ranks (e.g. 20th seat). This varies from division to division, for there are two 3rd Seats in the 13th Division. Seated officers often lead sub-units within each division (for example, 3rd Seat Hanatarō Yamada is leader of the 4th Division's 14th Advanced Relief Team).

Noble Families:

-Kuchiki Clan: A family of skilled Shinigami known to often serve Division 6. Known to wear special hair ornaments, and are in possession of a rich silk scarf worth a fortune. They are known to collect the histories of the Soul Society.

-Shiba Clan: A family of skilled Shinigami known to often serve Division 8. They are known to specialize in firework technology and whats known as "Primitive Kido".

-Ryudojin Clan: A family of skilled Shinigami known to often serve Division 13, and are accredited with the discovery and research of Blanks, the Dangai and dimensional travel.

-Kasumioji Clan: A family of inventors and noblemen that choose to serve often on Central 46 rather than as Shinigami. Despite this, the family can be credited with inventing various technologies such as Bakkoto, Denreishinki and helped create the Gigai.

-Ise Clan: A family of religious priests in possession of a hereditary Zanpakuto known as Shinken Hakkyoken. This Zanpakuto allows them to destroy powerful "god-like beings", but also causes many familial deaths.

-Kannogi Family: A lesser family of master dignitaries that have lowered in prestige recently, but are affiliated with the Kasumioji Family.

-Omaeda Family: A lesser family of rich Shinigami that often serve Division 2, and are accredited with the start-up of various businesses within the Soul Society.

-Kira Family: A lesser family of skilled Shinigami, that often serve Division 3.

-Ukitake Family: A lesser family of skilled Shinigami that often serve Division 7.

-Kyoraku Family: A lesser family of skilled Shinigami that often serve Division 9.

-Miura Family: A lesser family of skilled Shinigami that often serve Division 5.

-Sasakibe Family: A lesser family of skilled Shinigami that often serve Division 1.

Division 1: (Events/Generalists)

Division 2: (Stealth/Crime)

Division 3: (Backup/Reservists)

Division 4: (Construction/Healing)

Division 5: (Guardians of Earth)

Division 6: (Hueco Mundo Combat)

Division 7: (Rukongai Protection)

Division 8: (Bodyguards/Diplomacy)

Division 9: (Teaching/Tactics)

Division 10: (Fear Tactics/Combat)

Division 11: (Zanjutsu/Combat)

Division 12: (Science/Research)

Division 13: (Gatekeeping/Generalists)