"This was the first Hogyoku evolution already. I wondered how many times he could evolve this time, or whether five evolutions were the Hogyoku's limit."
Watching Aizen, whose entire body—including his head—was now shrouded in strange white matter, Shen Fei muttered silently to himself. The Quincy might not have noticed because their attention had been focused on him, but Shen Fei had clearly witnessed Aizen's entire resurrection process.
In the original work, Aizen's Hogyoku had evolved through five forms in total. However, no one knew whether five forms were truly the Hogyoku's limit, or whether Aizen had simply been unable to undergo a sixth evolution after Ichigo defeated him.
There were many theories about why Aizen could not evolve any further. For instance, perhaps the Hogyoku's energy could only support five evolutions. After all, not even the Spirit King's power could sustain limitless evolution.
Another possibility was that the Hogyoku had been destroyed by Mugetsu Ichigo's Getsuga Tensho, which stopped any further evolution. After all, that had been an attack beyond dimensions. Kurosaki Ichigo had possessed many forms in battle, but in Shen Fei's view, Mugetsu Ichigo had been the strongest—perhaps even stronger than the dual-blade Ichigo who later fought Yhwach. There had been plenty of debates about this in Shen Fei's previous life.
But in Shen Fei's opinion, Aizen had been unable to sense Mugetsu Ichigo's spiritual pressure even after five Hogyoku evolutions. The later Ichigo could not possibly have been stronger than that. After all, even while sealed, Aizen only needed to have a tiny portion of his seal released to use Kyoka Suigetsu to slightly affect Yhwach. That meant Yhwach's spiritual pressure had not rendered Aizen incapable of sensing it.
One could sense the other's spiritual pressure, while the other could not sense anything at all. The