There were three aspects that dictated Seong's existence in this dimension. The first two were Jin-woo's field of perception and how far Seong was away from that perception. The last one was related to Seong himself, and it was his own perception. Even if Jin-woo closed his eyes, as long as Seong could see him he could go anywhere he wanted.
Well, 'see' wasn't the right word to describe this aspect or describe it fully, since Seong was flickering in and out at the periphery of the chasing zombies, searching for a security guard, while Jin-woo was running from the zombies.
They weren't looking at each other, but Seong could still move about freely.
Rather than being able to just see each other for Seong to move freely, it was the concept of them being able to know where the other person's position in space was with absolute confidence.
