Maybe they can see what the world story on the Smartphone, or they saw some legend or something that a person with a smartphone that is strong but misunderstood that it wasn't about having a smartphone, and the smartphone is just an indicator that that person is a chosen by Arthur
That's kinda dumb, how can they know he reached his limit when his skills are unusual. He's just treading on uncharted path. Why didn’t he try to look at his own future
Let's read the title again but SLOWLY
I’m just a human but I was raised by the Four, four what?
Four HEAVENLY Kings, of the what?
of the DEMON King’s Army.
Hahahaha