Holy Guard

The Holy Guard is an organization of five powerful beings who have been assigned with protecting the Spirit Pool, and aiding with souls reincarnating. They are located inside of the Spirit Pool, (the location where souls wait to be reincarnated), and are never allowed to help the Gotei 13 or the Royal Guard in their assignments, unless both of them completely fails. Although the origins of the Holy Guard are unknown, some believe that they came into existance sometime long before even the First Shinigami Hollow War, which was the first war that Shinigami actaully took part in.

History
Although much of the history of the Holy Guard are largely unknown, it is said that Kenryoku Miyamoto, the first Spirit King, founded the organization thousands of years prior to the first Shinigami Hollow War, and that he served in it, along with his first born son, Sosuke Miyamoto, as one of the first actual members.

Mission
There have been a few specific duties noted for the Holy Guard:
 * 1) Protection of the Spirit Pool from outside forces.  If the wrong person is allowed inside, then numerous things could happen.  They could prevent reincarnation, thus distrupting the balance.  It's also possible, through intense emotional construct, to divide oneself from the cycle of reincarnation, maknig them monstrously more powerful, and one step away from an immortal.
 * 2) Helping souls to be reincarnated to and from the Soul Society and the World of the Living, in order to maintaine the balance.
 * 3) Helping the Gotei 13 and the Royal Guard in their duties ONLY when they have completely failed, and cannont complete them themselves.

Becoming a Member
The most crutial part about the Holy Guard is how to be accepted. There are so many stipulations in becoming a memberthat very few ever even come close to actually being able to join.
 * 1) A member of the Holy Guard has to have mastered the Shikai release of their Zanpakuto.
 * 2) A member of the Holy Guard has to have mastered the Bankai release of their Zanpakuto.
 * 3) A member of the Holy Guard has to have mastered Bankai:  Nijun for their Zanpakuto.
 * 4) A member of the Holy Guard has to have mastered the Omoimoyoranai Shinsou release of their Zanpakuto, thus being a Kami or Megami.
 * 5) A member of the Holy Guard has to have mastered the Royal Release of their Zanpakuto, thus having been a member of the Royal Guard.
 * 6) A member of the Holy Guard has to have, at one point in time, been a Captain in the Gotei 13.
 * 7) If an ancient, powerful warhero in the Soul Society wishes to be in the Holy Guard, but they were never a Gotei 13 Captain, then they still can; this bypasses rule 6 and rule 10, but not any other rules.
 * 8) A member of the Holy Guard has to be either a Kami or Megami, either full blooded or half blooded, in order to make rule 4, mastery of Omoimoyoranai Shinosu, even possible in the first place.
 * 9) A member of the Holy Guard has to, under most cercimstances, have not had a single offense in the Soul Society for a crime, regardless of the size of the offense.  Although this can be bypassed if rule 7 applies to them.
 * 10) A member of the Holy Guard has to have been a member of the Royal Guard at one point, in order to make the rule about having to have the Royal Release mastered even possible in the first place.
 * 11) Although not an outright requirement, if soneone is a member of the Royal Family and want to be in the Holy Guard, it'll make their chances much greater; this allows them to bypass every other rule, except for the requirements about the release commands of the Zanpakuto.

Retirement
Unlike the Gotei 13, which does not recognize a Shinigami's resignition, the Holy Guard, much like the Royal Guard, does indeed allow a member to retire from their position if they see fit. Once retired, the member can either return to the Royal Guard or the Gotei 13 if they wish, or just live out the rest of their lives in peace, living in luxury in their own personal section of the Spirit Pool.