Obbligato, but lean just a liiiiiittle bit harder into the horror aspects of it all. Because honestly, you've already got all the elements of a school-set gothic horror story:
Prestigious school which our everyman protagonist (Jun) has enrolled in hoping to change his station? Check.
Weird fucky shit that occurs at said school? Let's see we've got:
- the mysterious man who lives on the grounds that Jun can't get get a straight answer about who he is
- the isolation/imprisonment aspect of how the students can't leave
- the subhuman treatment of the non-honored students
- the way that students keep disappearing (cuz they're escaping right? right????? say we never got an answer about what meat Papa Tojou was feeding Jun, did we......)
Don't get me STARTED on how weird and kinda cult-ish Tatsumi Kazehaya's whole solution to the problem of the non-honored students' exploitation is. Yes, come to these fucking catacombs where I will preach to you and then let you become "me" by doing works! This is normal, not its own sort of exploitation, and definitely not something that could in any way lead to fanatacism, mass hysteria, and/or tapping into something actually supernatural. (God do I love shit that walks the line of "was that actually something otherworldly or was it just us all along?")
And then Kaname, oh, Kaname... A character through whom we see a humanized version of the honored students, not a self-made saint like Tatsumi, but a messy, fallible fool who eventually gets thrown into the mud and only makes it back out through the assistance of a mysterious, unseen benefactor who claims to be his brother...
The pieces are all there! All this weird, unpleasant shit, locked into the pressure cooker that is Reimei Academy, and just waiting for you to turn the dial one click spookier. It could be so good.
I don't know how exactly I'd wanna piece this together into an actual fic yet, hence why I wrote a text post about it instead. Could maybe work with some sort of framing narrative, such as Jun recounting it to Hiyori or someone else, but the continued existence of Reimei and thinking about the rest of Eden eventually being there sort of breaks my thoughts on how to make a cohesive ending happen.
...though that's it's own sort of horror too, isn't it?
Even after all he's seen, all he's survived, Jun can't/won't leave this damn school. He's worked too hard to turn back now, and that sunk-cost fallacy means that Reimei has a piece of him. It'll take a piece of anyone who will let it feed on their dreams for a thin chance at stardom.