In all things there must be balance, life and death are no different.The world simultaneously has a finite and an infinite amount of Souls in it. While the great masses shift between the World of the Living and the Soul Society, the weight of these ever moving Souls must be balanced between the two, as an instance of unbalance can rend a rift in the reality and time we know and bring us to the edge of a void that cannot be come back from. The Soul King and his retainers locked away in the Soul Palace keep this balance, shifting Souls between the World of the Living and Soul Society and back again when the balance shifts once more. A single Soul may see a million lifetimes in this way, moving through the millennia as they dance between the planes, between life and death. Some may only see two lives, their life in the World of the Living and their existence in the Soul Society. Others still are allowed to return to the World of the Living once more if they are chosen to return the balance of Souls to perfect harmony. Those that find themselves lucky enough to be graced with the Second Incarnation have a second chance at life in the World of the Living. Their memories of past lives stay buried within them, sometimes coming out in instances of deja vu and the like. These few lucky Souls will reenter the World of the Living as part of their once forgotten family, another child born as another Soul leaves the world. And so the balance remains as lives shift between the two, slowly drifting between life and death, a chaotic dance that brings beautiful results.
The Second Incarnation finds its beginnings in the days long before Genryūsai Shigekuni Yamamoto established the Gotei 13 or the Shin’ō Academy. It is assumed that the flow of Souls between the World of the Living and the Soul Society has stretched as long as the two planes have been separate, but no history exists from those before times to enlighten those of the Soul Society of the truth. As long as the Soul Palace has stood and the Soul King resided inside it, the Second Incarnation has existed, a timeless tradition of the planes of the living and dead. While little history exists of the early days, since the days of the Gotei 13 and their perchance for collecting history, some information about the Second Incarnation has existed in the archives of the 12th Division. Mostly scattered snippets and pieced together memories, the information about the rare and revered event gives a glimpse into what the honored Souls would experience as part of the process. Very little has changed about the process as is shown in the archives.
The Second Incarnation is rare, but it is an honored tradition that few Souls will ever see or know about, let alone experience.The process of the Second Incarnation is highly secretive, often only being known and understood by the Soul King and those that serve him. Souls are chosen seemingly at random for this process and can be highly celebrated or ignored in the Rukongai depending on their status before they make their way to the Soul Palace. Once a Soul has arrived at the Soul Palace, very little information from across history exists to explain what happens to the Soul at this point.
Soul vs Shinigami
Souls that have varying levels of Reiatsu often find themselves in the Rukongai when they first enter the Soul Society. The Rukongai contains a number of districts and is where the largest majority of Souls reside in Soul Society. In instances where a Soul has a high amount of Reiatsu, they may become Shinigami as in the cases of Lieutenant Renji Abarai and Captain Kensei Muguruma. Souls that do not become Shinigami are left to live out their lives in the Rukongai. This population is most commonly who participates in the Second Incarnation as these Souls are sent from their lives in the Rukongai to a new life in the World of the Living, whether they have died in Soul Society or not.
Shinigami are Souls with a high level of Reiatsu and often some measure of control over that Reiatsu. While a minority population in Soul Society, Shinigami also take part in the Second Incarnation, although in a much different way. Shinigami will never reincarnate in the World of the Living, only reincarnating as the child of a Shinigami or another Soul with powerful Reiatsu in the Soul Society. Due to the long lives of Shinigami, the Second Incarnation is extremely rare and has more stipulations than for average Souls. A Shinigami that dies will often be reincarnated within their own family, especially if the family has powerful Reiatsu or is one of the Noble Houses. If this is not possible, the Shinigami may reincarnate as a Soul with strong Reiatsu in the Rukongai, but this instance is more rare than the Second Incarnation occurring in Shinigami.
Culture of Soul Society
While reincarnation and the movement of Souls between the World of the Living and the Soul Society is commonplace, it is a topic that is very rarely spoken of. Those that die in the World of the Living transition to the Soul Society and begin anew, essentially starting over in a new life. On the other hand, those that die in Soul Society are treated and revered with a great respect as those Souls are considered having reached the end of their lives.
The Second Incarnation, while rare, is an event solely focused on the duties of the Soul King. Those that are chosen to begin the cycle anew in the World of the Living are taken to the Soul Palace and often showed in grand celebrations depending on their status in the Rukongai at the time of the transition.
All Souls in Soul Society are subject to the possibility of the Second Incarnation upon their deaths, but Shinigami often do not reincarnate in the World of the Living. Souls with high Reiatsu often find their Second Incarnation returns them to the Soul Society instead of taking them to the World of the Living.
Those that are chosen for the Second Incarnation are escorted to the Soul Palace with some measure of fanfare depending on their status in the Rukongai. Once they enter the Soul King's domain, they are prepared to begin a new life in the World of the Living, although the exact process is highly secretive and is something that Souls no longer remember have the instance it happens.