After deciding to begin investigating the Wandenreich, Asano Kiyoshi began a series of studies with Kisuke Urahara.
When Kisuke Urahara learned that a vast Quincy Empire actually existed within the shadows of the Seireitei, his intense interest required no urging from Asano Kiyoshi whatsoever.
After donning a black cloak, Urahara even established a small secret base within the Seireitei under Asano Kiyoshi's deliberate cover.
After several months of research, the two of them finally found a way to enter the world formed by those shadows.
The method of entry was both simple and difficult.
The principle was straightforward: within the space occupied by the shadows, they would connect with external Reishi and construct a passage leading into the shadow world.
It was a simple principle, but in this world, aside from Quincy, no Shinigami could truly accomplish it.
It involved absolute control over Reishi, somewhat similar to the Quincy's Sklaverei.
Asano Kiyoshi happened to be able to achieve this through his Zanpakuto's abilities. Furthermore, through years of fusion, he had basically absorbed the King's Seal's power completely into his body. His perception of space far surpassed that of everyone in Soul Society.
Even so, it still took Asano Kiyoshi and Urahara nearly a year to find the correct Reishi arrangement for entering the shadow empire.
It was a long passage arrangement composed of countless Reishi nodes. A single mistake at any point would only allow one to travel across the surface of Soul Society's shadows, making it impossible to enter the Wandenreich at all.
Those nodes had been calculated one by one by Asano Kiyoshi and Kisuke Urahara after innumerable attempts and failures. It had truly exhausted both of their efforts.
Once they successfully connected a passage to the Wandenreich, Urahara used the Reishi density and various data transmitted from