Do people not longer know what plot is? Guys complaining about world building are so ridiculous. Nothing in this chapter was a filler and tehy literally just introduced an important character who's clearly connected to the MC.
@ultimatehaki because the artist knows how the story's gonna play out from later LN volumes, he can add a foreshadow to the event like this.
LN and WN readers too are most likely to know what that shadow is.