Where to start? It's nonsensical.
Pretty much all of it boils down to one thing: The author wanted to progress through the story at Mach speed. Never did he take his time to write compelling plot points or at least some interesting dialogue. Everything about this manga feels like mindless and soulless action fodder. It is just so irritating because the concept behind Chainsaw Man had a lot of potential to be great.
At its core, CSM is an action manga, but the fights are weak. They are over way too fast, every single one of them boiled down to having a one-shot kill conclusion. That is not a bad thing per se, look at One Punch Man for example, but CSM handled it poorly. At least the fights are accompanied by some decently drawn s from time to time.
I just wish the action would feel more impactful and engaging, but it follows the same formula every single time. Humans are mostly red shirts and the whole power dynamic between devils is convoluted. But who cares, because Denji only has to rev up his chainsaw and the mind-numbing slaughter can commence.
Furthermore, the manga is stuffed with suggestive scenes and fetish moments because you need at least one thing to get the blood pumping for all the horny teens. At some point, it is just plain annoying, mainly the whole barking shtick.
At least it was a very fast read.
Characters
The characters are a disaster. At least in my opinion, not a single one was likeable or left a positive impression. Two characters were bearable, Kishibe and Quanxi.
My main gripe with all the characters is that they are just as shallow as a puddle. No development, no meaningful interactions and why would I care about them if they just get thrown into the meat grinder after a few chapters anyway.
Let's talk about a selected few characters in more detail.
Kobeni was a throwaway character. I think she is supposed to be cute and a bit hopeless, maybe even a bit of a comedic relief. For me, she just appeared to be irritating and laughable, especially in the hotel arc.
Now, Denji, the star of the whole ordeal. Well, he is terribly written. His main motivation was always inspired by sex, that's it. To be fair, Denji is a hormone-driven teenager, which is also probably the target audience. Thankfully, he realized at one point that sex alone might not be the greatest goal ever.
As the main character, he just had nothing going on for him that would make me like or even just tolerate him. No personality whatsoever, though, at least the author tried to introduce more character depth for Denji in the last few chapters with the help of Power but that just felt rushed and forced.
Talking about Power, what's the point of her character? What did she bring to the table besides acting as a wish fulfiller for Denji? She got my interest at first because she showed a bit more depth but that was scrapped real fast and she turned into another useless side character.
Last but not least, Makima. I already mentioned the whole barking shtick but it was just so tiresome. Her seeing Denji as nothing more than a dog got tiring real quick. Besides that, I don't have any strong feelings or opinions about her. I mainly was confused. I don't understand her motivation, it makes no sense to me, and her power level was way too high compared to everyone else. Her ruthlessness was the one trait that kept her somewhat interesting.
Art
Most of the art is below average. Nothing stood out in a major way and it sometimes felt like flipping through a sketchbook. I don't need perfect and polished art on every page but give it at least some sort of uniqueness or "spice". Some fighting s were drawn with a solid style, but those were used only once every blue moon.
Although, I actually give credit to the author for the devil designs. Most of them were pretty solid and didn't get repetitive.
Overall opinion
I can't mention anything positive about this manga, therefore I'll keep this part short. I don't get the massive hype around CSM. It's not the worst manga I've ever read, but it disappoints in so many areas. The writing is subpar and the art is, for the most part, uninspired.
Still, I'll check out the anime because it is made by MAPPA. The CSM anime will probably be like a Michael Bay movie. Solid visuals while everything else is a dumpster fire.
