```
"No matter what it is, there must be a reason!"
Xu Yang looked at Jun Qing and asked in a deep voice, "It couldn't have appeared in this world without cause."
"Indeed!"
Jun Qing nodded, then added with a wry smile, "But just like the true nature of the Chaos Yuan's Air, apart from the Immortal Emperors and Gods, I fear no one knows the cause and reason behind its appearance in this world."
"Is that so?"
Xu Yang muttered to himself, not surprised, and simply changed the subject, "Then, when did the first signs of this Demon Catastrophe appear?"
"Hm!?"
Jun Qing's eyes narrowed as she asked solemnly, "What do you mean by that...?"
"There are things for which we must prepare for the worst!"
Xu Yang's expression remained unchanged as he looked at Jun Qing with a smile, "Would the fairy agree?"
"..."
After a moment of silence, Jun Qing nodded and said with a light laugh, "Exactly so!"