With the way he's set up like an extremely powerful end-boss type (again, "lifeless king" or "elder lich") I highly doubt he's just going to end up a throwaway villain. The big problem I see is that he's a really terrible villain so setting him up as the main antagonist (even if just for a while) doesn't fill me with excitement. Establishing a villain like this isn't a bad thing in itself - like as much as this arc has sucked, at least stuff is happening in it even if really stupid and really slow-paced - but the issue is that Julius is written like complete trash.
He's super mysterious, super smart, always ahead of the others and planning around what other people are planning about him, and also a super undead that appears to be extremely powerful and functionally immortal. From a narrative tension aspect this basically means our OP teacher MC Washio is likely the only one that is remotely relevant in terms of an even conflict with the guy, leaving all other characters as "moral support" (aka useless).
Even in stories where both the good guy and bad guy are OP in comparison to the normal person, there can still be an interesting story told based on the beliefs and personalities clashing with each other. Unfortunately Julius fails there too, as he's just mysteriously evil for some reason that hasn't been given. All we know about him is that he deeply enjoys seeing others in despair... and that's it. No other motivations for doing what he's doing, nothing on why he's targeting the school, targeting Washio or his monstergirl students, etc. We can certainly sit here and speculate (as we have for many previous chapters), but the point is we're almost 40 chapters in and barely know anything about Washio or Julius (and they've barely interacted with each other prior to this) so the "conflict" between them feels extremely hollow.
This story really needs to either flesh out this character real soon, or drop him entirely - and I have a feeling that neither will happen.
