Hihi novel reader here! He actually doesn't knkw yet but has a clue already—there was a chapter before 100 that J told sayoung(artisan & student was also listening but not jung bin since he was knocked out from the injuries) that
'Tell them J is back' yeah and up until chapter 114? I think euijae still didnt know sayoung was the kid until that part and yeah ahhaah(brace your selves especially when the manhsa reaches the 260+ chapters SPECIFICALLY at chapter 300+ onwards cuz it is HARD.HARD.HARD...)
Also spoilers the systems etc will disappear at the end but the reason why? Secret~ u guys gotta endure what I went thru(▰˘◡˘▰)

Does he know that he’s J? Or is it still a secret