A very common argument against most of popular and semipopular (especially battle) shonen that comes and goes on the community is the pacing dilemma. As the series starts to throttle to an end, or either expands on its thematic and metanarrative endeavors, the sense of universal time almost always goes away in favor of either fighting scenes, character moments or sporadic dumps of world building. Or all in-between, which don't further let the main story advance.
Most people see these as filler instead of taking into account how well the sense of place its conveyed to the reader, which is actually a pretty hard balance to strike - and I'd argue is the backbone of interesting places to visit, no matter how mundane or simplistic it ends up. Folks tend to say "showing is better than telling" but its actually more like "show AND tell is fucking great".
It's the fear of running out of steam that feeds on that very steam defueling because of caring a bit too much about the story itself rather than its elements from most of the audience. Well, Immortal Regis seemed to take a lot to account for in this regard and did not want to stretch itself out to ad nauseam, to the point it doesn't really have a story arch, but rather a jumbled mess of introduction to its magical world and... class system, just to inmediately throw it all to the Sun maniac-style and present the "war arch" archetype right out of the gate to tease a new war arch on a second season.
What this ended up generating is a very noticeable disconnection between the story told and the happenings shown. Well, yeah, if you skeem through it hastily, enjoy its admitedly scratchy, attractive and very female-candy artstyle and direct dialog, you'll get a protective-brother narrative with a sprinkle of romance at some end and a high-stakes cliffhanger. However, as soon as you try biting a bit further and enjoy the world and characters surrounding it, that's all you get - skeletons of stereotypes fitting their role, a vacuum-sealed magical world that surely tells us a lot about it but you can't really picture in your mind on a meaningful way.
Sure the ladies are attractive -oh they are, I love them- but I cannot give a shit about them because they've been dumping info and kinda sticking with the main character by default without an actual depiction of them breathing outside what it's been told. Why does the MC ending up caring about what some chapters ago he himself said was her resource? Why is she caring about the undead when some chapters ago he was just a looot of political trouble to her? There's a semblance of a romance plot growing but it's lost because it goes incredibly fast while losing itself somewhere. The students despised between each other, and the manwha does an attempt at bringing prejudice, but then forgets about it? Which is fucked because the MC being an outcast is... kind of a big deal for the WHOLE story being this short? This isn't Izuku Midoriya's quirkless situation - at least archs like the School Festival gives tone to the space 1-A lives by, goofy and carefree when they can because they're kids, the bullshit left to adults.
I have to guess there are palaces, schools, economic and industrial residences, class divisions, continents, by my own? Because there is something on the panels, strange jungles and vatican cities and gothic structures and noneuclidean spaces. How much of them stop being a mere asset to play with?
Everything feels incredibly loose in Immortal Regis, and wasted because of it. So much development that I can't picture nor it tells me I should care anyway. Nothing has the weight it should because it's preoccupied on presenting its happenings in cool ways and upping itself beat by beat, panel to panel, without a second to let characters talk between each other stuff that isn't contextual chatter or the next narrative goalpost. It's like I'm playing a 2000s action RPG videogame with none of the spatial design, metanarritive and interaction.
Seriously, this is the kind of manwha that makes you appreciate the existence of side stories and silly story archs in other places. This is what happens when you cook your french fries way too fast - sure the crunch is wild but there is barely potato taste on them, only charred oil.
What a shame, the girls are sexy as hell and Serin is genuinely a cool character.