"Going to Hueco Mundo, there's no guidance from the Hell Butterfly," Shihouin Kongchan explained as they moved through the Boundary. "To reach it, we must rely on our own Reiatsu to condense a path beneath our feet, otherwise we'll lose direction."
In the strange, grey silence of the Boundary, Kongchan addressed his companions: Gosuke Shigure, Yoruichi, and Zaraki. As a veteran Shinigami, Kongchan had experience—he had stepped into Hueco Mundo before. But the others, including even the current Kenpachi, Gosuke Shigure, had never ventured into that hostile world.
At least, that's what Kongchan assumed.
But unexpectedly, Gosuke Shigure showed complete ease in manipulating his Reiatsu to condense the path beneath him, something that took Yoruichi and Zaraki several moments to master. Kongchan silently praised him: As expected of a captain… Truly exceptional.
The passage through the Boundary felt long. Though only moments pass in Soul Society and Hueco Mundo, time in the Boundary flows differently—at a terrifying 2000:1 ratio. Every hour outside equals over 2000 hours within.
Thus, what felt like days of walking through the silence was, in reality, the span of a few breaths outside.
"This is it," Kongchan eventually said. "Hueco Mundo lies ahead."
Just as he prepared to open the boundary and step through, a sudden storm of dimensional force erupted. Such occurrences were not rare in the Boundary—violent anomalies that could scatter even captains.
Kongchan braced for impact but was still torn from the others. In a flash, they were separated.
Gosuke Shigure was one of the first to step out into Hueco Mundo.
Yellow sand stretched endlessly before him. The sun—unnaturally still and scorching—hung heavy in the sky. There were no plants. No life. No breeze. Only stillness and heat.
Hueco Mundo, as ever, was a world of death.
Despite the high spiritual particle density in the air, the land was unsuitable for Shinigami. The Soul Society, in comparison, was far more livable. Hueco Mundo was harsh, brutal, and desolate—a natural home to Hollows, but not to Shinigami.
Gosuke glanced around and muttered, "No matter how many years pass, Hueco Mundo doesn't change. Still as barren as ever."
Then he frowned slightly. "Separated again… Is this a curse? Every time I come to Hueco Mundo, I get split from the group."
He remembered how, in the original timeline, captains like Zaraki, Unohana, Mayuri, and Byakuya had all been separated during their support mission to rescue Kurosaki Ichigo. It seemed the chaotic nature of the Boundary made such things inevitable.
Just then, a presence emerged beside him—a Hollow.
A hooded, freshly-born Hollow appeared, drawn by the rich spiritual scent of a powerful soul. Its hunger flared.
"Delicious soul…" it muttered.
This Hollow had likely never seen a Shinigami before. And now, in the presence of such immense Reiatsu, it lunged—mouth open, hunger overwhelming.
But before it could strike, a flash of steel appeared.
Shing!
The Hollow froze—cut cleanly through. With the purifying nature of a Zanpakutō, the creature's essence shimmered briefly and then vanished into reformed spirit particles.
Normally, slain Hollows would be purified and sent to Soul Society. But here in Hueco Mundo, where the world itself devours and repurposes everything, that spirit energy was absorbed back into the sands, nourishing the land itself.
So that's why the spirit particle density here is so high… Gosuke realized.
Hollows consumed souls from Soul Society, feeding their power into this realm. And when they died here, they returned their spiritual energy to the land. Over centuries, this cycle bloated Hueco Mundo with excessive spirit particles—so much so that it threatened the balance of the worlds.
That's why, from time to time, the Soul Society had to purge Hueco Mundo. If left unchecked, such density could give rise to monstrous beings capable of threatening existence itself.
After purifying the Hollow, Gosuke sighed and looked to the horizon. Better find the others.
He began to chant softly, forming the incantation for a high-level Bakudō.
"Bakudō No. 58: Kakushitsuijaku!"
Using the spell, he spread his senses outward, searching for familiar Reiatsu signatures.
Just then, a flicker.
There!
Someone else was casting the same Bakudō—likely Yoruichi or Kongchan. Their spells collided briefly in the spiritual plane, and in that moment, they became aware of one another's presence.
A smile tugged at the corner of Gosuke's mouth.
Found them.