These two...
Gaoyu knew them, yet he didn't.
He knew them from the manga, but he hadn't seen them in this world yet.
A man and a woman, one tall and one short, neither wearing the mask that marked them as Hollows, despite being in Hueco Mundo.
They wore tattered cloaks, and at that moment, they seemed to have noticed White's presence as well.
Those features were simply too distinctive.
Stark and Lilinette Gingerback—the future Number One Espada.
Aizen had noticed the two of them, too. A hint of curiosity and surprise appeared in his eyes.
"Strange. Why would there be Hollows without masks in Hueco Mundo?"
Gin Ichimaru said curiously. He looked at Aizen, apparently thinking Stark was one of Aizen's experimental creations.
Aizen's lips curled upward. "Is he looking for something 'opposite' to himself? An autonomous Hollowfication among the Menos Grande, too. How interesting. Could we... go over and take a look?"
Gaoyu understood what Aizen meant.
White had originally been a Shinigami's soul, but Aizen had used his techniques to transform him into a Hollow.
Stark, on the other hand, had originally been a Hollow's soul, but for some reason, he had undergone the process of Hollowfication.
Hollows had holes in their bodies, and those holes represented the emptiness in their souls—their hearts, so to speak.
So where had the missing part of the soul, that absent heart, gone?
It had become the mask on a Hollow's face.
Hollowfication involved breaking that mask and turning the part of the soul it represented into a Zanpakuto of one's own.
Before Stark, no Hollow in Hueco Mundo had ever been able to break the mask on their face. No wonder Aizen had taken an interest in him.
The Arrancar Aizen wanted to create were "Shinigami-fied Hollows." He had started