Reading murim and cultivation manga has become a bit of a guilty pleasure for me, and I've since read many amazing works, as well as an equal—if not greater—amount of subpar or simply bad ones. The quality of the Murim/Cultivation genres tends to fluctuate wildly in every aspect, from the art to the story and beyond. Sometimes, I keep reading a manga even if it's of poor quality because there's something mildly interesting about it—some sort of quirk or hook. Some have unique and interesting artwork; others have engaging storylines or fascinating characters. However, I'm sad to say that Nano Machine has been extremely uninteresting to me and lacks any of the aforementioned qualities, despite being one of the highest-rated and most popular series in the genre.

The Heavenly Demon Cult plot is a classic by now. Plenty of other manga use the same plot point but add a twist to make it unique. For example, works like Heavenly Demon Reborn, Myst, Might, Mayhem(Same Author as this), or even manga where it is not the main focus such as - SSS-Class Revival Hunter - have more interesting takes on the Heavenly Demon Cult and the Heavenly Demon concept.

I'm not too fond of adding nanomachine technology to murim/cultivation manga in general, unless it has other redeeming qualities or is simply played for comedy. More broadly, I’d prefer if cultivation manga avoided “cheat systems” entirely—especially those given only to the main character—because it undercuts any sense of satisfaction when the protagonist accomplishes something (it all just goes back to the cheat system). Even among cheat systems, however, I found nanomachines particularly silly. I researched a bit, and the protagonist receiving the system is explained in another work by the same author, but I don’t think it works well in Nano Machine as a standalone.

Its worst aspect is not that it’s “very bad” because that can be entertaining in its own way; rather, it’s simply extremely boring and repetitive. It’s hard to connect with any of the characters. Most of them are bland, uninteresting, and one-dimensional. The protagonist lacks any real depth, and if you remove his nano system, there’s very little to justify why he’d even be an interesting side character. I don’t mind gore, but the frequent arm-cutting became comical. The main character bounces between murdering innocent people and being compassionate without any introspection about his actions. The way he powers up—through “dual cultivation” with Yeo-Gun Wang—also feels cheap and lazy, creating a story scenario where the protagonist basically has to sexually assault a character to save their life leaves a really poor taste in my mouth.

At least in Myst, Might, Mayhem, we learn that the protagonist is basically a psychopath who feels alive when he commits horrible acts, which builds character and tells us something about him. I don’t particularly like a main character like that—it's a bit too over the top for me—but at least it has substance. Myst, Might, Mayhem also features distinctive art and a power system involving spirits, both relevant to the world it creates. Even though Nano Machine is meant to be a sequel to that, it fails on many fronts compared to its predecessor. The art is probably its strongest point, but even that isn’t appealing enough to keep it interesting.

Even as a power-fantasy it falls short. The power scaling later becomes so bad that no battles feel relevant anymore: Cheon is so powerful that even multiple peak-level fighters can’t challenge him. There are plenty of ways to handle an overpowered main character without destroying all sense of tension, but Nano Machine doesn’t pull it off. The story would have been better if it had ended after he got his revenge and became the Heavenly Demon; that would've wrapped things up nicely atleast. Instead, we’re left with bland characters and a godlike protagonist doing whatever he wants in a boring story.

Having completely lost interest; I decided to drop the manga around chapter 220+. I hope others can find enjoyment where I could not.