Ngl, I'm confused as hell about the structure of this world. I can only assume that the tutorial area is the base of the tower and there is a whole world outside the tower, but somehow Kahn knew that Cain, or whatever his actual name was, is from a different world. Maybe the tutorial area and the reason why he went directly there was explained at some point and I just glossed over it, but it seems like certain parts of the novel, as the TL pointed out, are being skipped over. Then again, maybe I'm just an idiot.