- "If Yhwach was the originator of the race known as the Quincy, then the Soul King can be called the source of the very power of the Quincy. Whether the Soul King had left behind an actual child before he was sealed or whether the 'power' that was stripped off the Soul King had manifested in the form of a person, I couldn't really say."
- —Tokinada Tsunayashiro
Tenson Kōrin (天孫降臨, "Advent of the Divine Descendant") is a phenomenon denoting the reemergence of the Soul King in the form of a living being after he was sealed as the keystone of the three worlds — Soul Society, Hueco Mundo, and the Human World.
When the Soul King's power was destroyed by the sins of the Five Noble House ancestors, it had splintered off onto the three worlds that were created by that power and would eventually manifest into the form of a person in each of those worlds. These individuals would become known as the "children of the Soul King" (霊王の子供, Reiō no Kodomo). They would inherit his powers, including that of The Almighty, and had become incarnations of his spirit. These children were born spontaneously through immaculate conception, born to women in those worlds and were typically revered as a holy event, particularly in the human world where certain religions were established based upon such phenomena.
Within the Soul Society, whenever this being had emerged, the Royal Guard had murdered the pregnant woman before the child could be born. It was said this was the will of the Five Noble House ancestors, who feared that the Soul King's power would return in the form of a successor to seek vengeance and, in doing so, destroy the balance of the three worlds. Each time the unborn child was killed, that power would once more reincarnate elsewhere. Eventually, the Royal Guard failed to prevent the successful birth of the next child, which would be that of Kamui Kawahiru and Seireitou Kawahiru. It was an unusual situation. In every other case, only a single child was conceived, but in this case, two children were born. However, as Ichibē Hyōsube noted, only Kamui had inherited the Soul King's power, while Seireitou did not. Instead of executing the newborns, Kamui was taken to be properly raised as a loyalist to the Soul Society, while Seireitou was discarded to the Rukongai, having been written off as a defect that was born as a mistake. The mother of the two children, Tsuyuri Kawahiru, was also taken into their custody.
However, in the human world, the Soul King's child was more familiarly known by the folklore of the Quincy born every decade that was unable to harness reishi. However, once Yhwach was born, there would not be a Quincy born like that for at least two hundred years. It is unknown exactly what was the cause for the circumstances of Jugram Haschwalth, though it is presumed there is a connection between this phenomenon and the reason behind the power shifting relationship shared by Yhwach and Jugram. Ichibē had briefly pondered if perhaps the reason behind their connection was a similar circumstance for why both Kamui and Seireitou were born together. Ultimately, he theorized if perhaps the Soul King's power was reemerging as dualities rather than solitary individuals.
It is unknown what child, if any, was born within Hueco Mundo.