Random recommendation time. Haven't done this in a while; haven't had one that hasn't already been recommended already that I thought was good enough or didn't get abandoned before I cared to do so.
かくしてはをける ～もももるなったなるの～
Story premise itself isn't anything new, with extremely low caste boy with almost nothing to lose goes on reckless adventure to get stronger to get what he wants. The twist here is, sad as it is, unlike most other Narou novels in the same vein it has actual effort. Characters have personalities and backstories including personal motivations, it has world building and foresight, and it's been pretty decent at conveying action. The MC himself doesn't just stumble into power, nor does he even have any sort of special ability due to birth (at least nothing revealed yet), which is a nice personal plus.
The subtitle itself is misleading. I'm sure it'll happen eventually—it hasn't yet, as it's a steady growth story—but whenever I see a story that has 'hero' or 'demon king,' let alone both in a title, I get wary; those ones tend to be particularly thoughtless and bad. I can only assume the subtitle itself a bid to attract the attention of the habitual low attention Narou fanbase. Unfortunately it doesn't seem to have worked in spite of daily updates with decent chapter length. It's also harem but frankly the harem elements are fairly minimal.
I'd say the biggest strength the series has compared to most the stuff I tried to read over the past couple years on Narou is it's able to keep my attention. Just fun to read. No random long filler chapters of trying to build onsen and eat rice while praising isolated eastern island nations, and enemies aren't just comedic elements or complete jokes. If I had to list a con, the MC in particular gets stronger as the series progresses but it's also kind of hard of to tell that he does. Can't necessarily write it off as poor depiction since the MC is always fighting mobs way stronger than him, with the trash mob fights happening offscreen 99% of the time.
Hope it gets serialized, especially considering the low bar for it nowadays, but I regrettably don't think it has the popularity numbers to get one. Would be nice to be wrong.