The Twisted Heavenly Bulwark is under attack.
The Celestials were already on the move. Their activity couldn't be hidden due to how big it was. Moreover, they do not have any intentions of keeping their movements hidden.
They were trying to punch a hole into the world's barrier. Such activity was bound to cause a huge commotion. Of course, since the Celestials weren't deliberately trying to hide their actions, the Hypogeans were also alerted by their movements.
It's not surprising that the Demon Emperor would know it right away.
And much to everyone's surprise, the Demon Emperor chose to follow suit instead of confronting the Celestials first.
There were a lot of demons who doubted the Demon Emperor's intent but didn't dare to say anything to not provoke his ire. Because judging from the aura he's released pretty recently, it is as clear as day that he's in an awful mood.
