Chapter 1261 Those Who Once Sent The Worlds Into Turmoil part 2
Serafall just smiled upon Aizen's question, "What do you mean?"
"Urahara showed me some of his memories and it looks like he wanted my assistance to deal with that mechanical being trying to invade your world." Aizen paused for a moment before continuing, "However, I've been thinking back to that moment and concluded that that thing does not have a soul. They have something else entirely different. Combining that with its strength, I'll just become a common cannon fodder the moment my ability doesn't work on it."
It was hard for Aizen to admit, but he was sure that his only advantage against the mechanical being that Ophis fended off was his undying body. Everyone in this world could cut through physical objects, however, whether they are a Shinigami, Fullbringer, Quincy, or Witch, they are far more effective against Spiritual Beings.
It's the reason why everyone has to expend a bit more effort against insect invaders.
Yhwach's Almighty may be useful because it's an ability that he uses on himself to see and control the future but that couldn't be said the same for Aizen, 'Against soulless beings, it might be interesting to study them, but I won't accept a one-sided beating.'
"Even if you use the entirety of this world's help, it'll only be a small helping hand against those things. At most, it'll be a standstill because they probably won't be able to do much against those with strong souls. After all, Spiritual Power could only be fully countered by another Spiritual Power..." In the middle of speaking, Aizen had a sudden epiphany. With furrowed brows, his voice trailed, "Unless..."
Serafall's smile disappeared and sighed, 'I guess it's about time for them to be properly filled in. In the first place, they are not a part of this world's defense.'
"Ehem..." Serafall cleared her throat first, "Let me preface this first by saying that we have no intention of controlling your freedom, Sosuke-chan. We know that if we try anything like that, you'd be one of our biggest problems and we don't really like taking on unnecessarily difficult ones."
Aizen was a bit taken aback by the way she called his first name but didn't say anything about it and just continued listening.