But what about the opposite problem? How do Evil Spirits from the Far Realm observe humans in the real world?
The most common explanation is that, even for Evil Spirits, cognition is still based on the exchange of information: just as radar confirms information by "emitting electromagnetic waves to illuminate the target and receiving its echoes," Evil Spirits use their perception abilities to recognize the real world—and this ability is almost equivalent to human Spirit Communication Ability.
Since they are observing from the perspective of the Far Realm, they cannot be blocked by existing technological methods, and no camouflage can be effective.
In short, Evil Spirits can directly discover humans through Spirit Communication Ability, while ordinary people need a series of indirect phenomena to notice their existence.
