This is a rule of the system type.
If Xiang Beifei had to describe it, it would be more like the system rule created by Zhu Yiji's "Square and Round Rules". The moment he tried to disclose the secret, his speech would be directly controlled, and a strong aura would be immediately emitted to notify the person who was exercising that ability.
Not only that, but as the aura enveloped him, he felt as if he had established an invisible connection with someone.
This meant that no matter where he went, he would be under the surveillance of that person, who could even use this aura to directly locate him!
The man in charge of registration saw that Xiang Beifei was cooperative and his expression softened a bit. Then he put a bracelet on Xiang Beifei and said, "Don't wander off in the desolate beast breeding base. Some desolate beasts here are highly aggressive, and you are just an S-class at the Meridian Opening stage. I don't want you to lose your life here."
