The corpse had no shadow. From the look of things, perhaps the shadow was this person's true body.
The change in this person's appearance, along with the earlier game text about Granny Tang becoming a Shadow Fiend, had also described her appearance changing into the shape of the shadow before announcing that she had become a Shadow Fiend.
This form of transformation reminded Mu You of "skins."
Players entered the Star Spirit World by projecting a virtual Thought Avatar into it. If that Thought Avatar found the corpse of a Native in the Star Spirit World, whether someone who had died in the past or someone just killed, it could "equip" the corpse as a skin and take that Native's place.
Since players could enter the Star Spirit World as game characters, could people from the Star Spirit World invade Earth using a similar method in reverse?
If shadows were treated as skins, people from the Star Spirit World could obtain an Earthling's shadow through some method, then use it to assume that Earthling's appearance, secretly hiding on Earth and working and living normally among humans.
Mu You suspected this because when he had examined the young man with glasses earlier, no game ID had been returned.
If that person was actually from the Star Spirit World, and the young man with glasses he had seen was merely the other party's "game character," everything made sense.
The muscular man Lin Xue had killed was also merely one of that person's "skins." By sacrificing this skin to save himself, his true body-the shadow-had escaped.
"I'll check the shore," Lin Xue said, then ran toward the sea with her sickle.
The direction that person had tried to flee in earlier had clearly been toward the shore. If he had escaped through his