Beneath a vast plain in the Land of Rain lay an enormous underground cavern, so immense that it seemed utterly beyond the power of human hands to create.
It was like a divine miracle left behind in the mortal world by the gods.
There, a momentous experiment that would determine the future course of this world's fate was currently underway.
Within the massive subterranean cavern stood rows upon rows of interconnected laboratories.
At that moment, a tall figure walked slowly toward one of the laboratories, a faint smile curling at the corner of his lips as his deep eyes watched the room ahead.
When he entered, the researchers working inside were all stunned and hurriedly called out in respectful surprise.
"Lord Aizen!"
"Lo... Lord Aizen is here... Look!"
By then, Kazumi was no longer the only one conducting research within the institute.
Kazumi, who had handled the foundational research in the early days, had now become one of the chief directors of the entire underground research facility. Together with Orochimaru, she led and supported the entire Great Hollow Era project.
Naturally, such an unimaginably massive experiment required far more than a handful of researchers.
Kinnara was responsible for acquiring them, recruiting some from various nations and abducting others.
Thus, the underground research facility gradually came to possess dozens of experienced research experts.
All of this had taken place silently in the shadows, without anyone noticing.
As the leader of the Land of Rain, Kinnara had spent all these years concealing Amegakure's strength. In secret, however, it existed in a symbiotic relationship with Las Noches.
The underground laboratory of Las Noches trained batch after batch of elite ninja for Amegakure.
After Aizen's return and the official launch of the Hollow experiment program, suitable boys and girls were selected from Amegakure for