As a Tier Four Scholar, especially when in the Yin Spirit state, he's extraordinarily sensitive to various peeking. When He Kao "looks" at him, he also senses it, turning his head towards the direction of the Shadow Mirror's observed angle.
That was merely the perspective locked in by the mirror reflection, and the Shadow Mirror was not in that position at the moment, so Erji didn't notice anything, but he vanished alertly—his consciousness instantly returned to his body.
The place where he hid was on the slope of Bai Ma Mountain outside the amusement park, within the crown of a large tree. This location is approximately 1.5 kilometers away from the target, precisely within the range his Divine Sense could reach.
Erji had just opened his eyes and found himself locked on, a pervasive feeling from all directions; it should be some kind of array. He looked up suddenly, and not far away, on a tree branch, stood a person!
...
