Crack, crack...
The sound of shattering glass reached Su Xiao's ears. He was struggling to suppress the derivative effect of the Swordsmanship Grandmaster ability. It was extremely difficult. He had to make sure Aizen had already left, but he was under hypnosis and couldn't determine whether Aizen had gone far.
A full ten minutes later, Su Xiao finally could no longer suppress the derivative effect of Swordsmanship Grandmaster. With a loud crash, the world around him shattered like a mirror.
As it turned out, Illusion's mental ability was completely ineffective against Su Xiao.
Don't assume that being able to break Illusion meant one could fight Aizen. Even without the Hōgyoku inside him, Aizen's strength was among the highest in the Gotei 13. Without this ability, how would he dare emerge and openly challenge the Soul Society?
The world around him returned to normal, but Su Xiao's eyes remained tightly shut. He was sensing whether the world around him was normal.
After confirming it repeatedly, Su Xiao was certain that he had escaped Illusion's hypnotic control. However, there was one highly troublesome point: if Aizen tried to control Su Xiao with hypnosis again, the situation would be extremely awkward. Of course, Aizen would be the awkward one.
Su Xiao now belonged to the Seireitei faction. As for whether he would join Aizen in acting against the Soul Society, that remained to be considered.
The greatest benefit of joining Aizen was that Aizen wasn't a paragon of virtue. Even if Su Xiao's methods were extreme, Aizen could accept them easily.
The benefit of joining the Seireitei, meanwhile, was that he could cling to a powerful backer. The Soul Society was not something Aizen could shake. Even after using the Hōgyoku to increase his strength, Aizen still couldn't easily shake the Soul Society.