MyLittleBrother
Sigh, some end game plot info is released and the MC is still pathetically weak.. I wouldn't have a problem with this if it was around 200 chapters. We are almost up to 900... This story is taking far too long and its extremely worrying reading content like this. The MC power progression is still extremely low for 800+ chapters.
Maybe the Ancient demon is the anchor for demons to descend into the 9 realms, so Divine Paragon has to draw it out to kill it. He said himself that demons are truly immortal and he let the escaped demons go even though he knew where they were. He might've realized this while slaying in the Demon realm, so he left and sealed it.