Please read Kaguya-sama. This sentiment is one that my friends have heard tediously often, but it is heartfelt. I think this series is worth giving a chance to even if you aren't into romance or comedy, since it genuinely is one of the most earnestly subversive and impressive stories; one I definitely didn't expect when I learned about it as "Death Note if it was a romcom." For me, the evolution of Kaguya-sama across its 281 chapters surpasses any other story that I know.
So if you do happen to find yourself uninterested in the sketch-based storytelling at the start, keep in mind it will be a different story by the end. Not only impressive in the development of the main relationship, but other characters as well, or even in the references to psychology and other fields of life. It's difficult to describe as it's rather unique.
Well, this is the gist of the promotion for the series that I want to give without spoilers, which I suggest to avoid if you're confident about starting the series.

BEWARE OF SPOILERS FROM HERE ON!

Having finished the first season, it seemed like I had grown really fond of the show, so I thought at least. But it turned out the impression it had left faded quickly and my reading of the manga got through only four chapters beyond the adaptation, leaving the series a mere landmark in memory.

Then the second season rolled around and immediately I was captured again. But I noticed that the story flowed differently. It had the same personality but it felt new.
Not only did the episodes share a common cast of characters and ideas, but the events of each episode explicitly influenced the following ones in a way that S1 only did for the climax. As the episodes unfolded, I saw the 67th student council disband, running in the election, winning, gaining a new member, Ishigami joining a school club, Kaguya almost addressing her feelings... Practically everyone was shown or explored from a new angle, while also introducing a sense of time, resulting in the show ceasing to be episodic, and what felt like getting closer to the "real version of it." When season two ended I had more than enough resolve to catch up with the manga for real.

Well, I read the manga. But honestly, I didn't notice that I did because I was so lost in the waves of ups and downs that is the story post sports festival. I forgot it's also a comedy. I may have forgotten it's a story. The experience of seeing characters whom I care for so much tussle with the ongoing changes in their lives was so immersive and real that it eclipsed everything. I read it over two days but it was probably a majority of it that I was locked in front of my laptop. Didn't feel sick later though and had found a new story tied for my favourite.

"This story has been serious for quite some time now." - Akasaka Aka.

How can a story simultaneously live and breathe in the realm of comedy and in themes of self-doubt, self-loathing, regret, guilt, depression, maturing, affection, so seamlessly...? I don't know, it's a great question and as a writer I yearn for the keys to the kingdom. But I do have an idea.

The main concept, which this essay is about, is that Kaguya-sama as a story is very whole; intermingling all of its elements into a very cohesive experience, and has a very strong personality, which makes it avoid binding itself down to storytelling conventions, genre, or its own initial structure. These two characteristics show in all major aspects of the story, which I'll go through.

The comedy.

Instead of being the main charm or just an accompanying element, the comedy is rooted into both the plot and character development. In so doing, for example: Ishigami's misunderstanding of Tsubame's question leads to an arc of Ishigami working on himself and Tsubame pondering on the nature of relationships; Miyuki's obscure skill issues form a series of episodes which uncover his deepest insecurity; Hayasaka's blunt commentary is almost her job. It doesn't feel like the humour or punchlines are being crafted by the author as much as them being a natural outcome of the bunch being together. I don't think anyone goes off character for a joke either. And while not every gag or joke is consequential, the idea is that comedy is not insulated into a space where it carries no weight over the story as a whole.

The characters.

I think that the factor which is shared the most by great stories is that their characters feel like people. But they are nurtured differently by writers, so it's possible to spot characteristics in casts of characters and compare them.
In this case, I find them written in a very broad way. Taking the main character, Kaguya, has many sides to her. IceGuya, BakaGuya, Child Kaguya, Chibi Kaguya, and Kaguya. Right? That's the representation of it and I love how it creates the Ice Kaguya arc, but it's also applicable in a more casual way, chapter by chapter. She's a genius and an absolute baka, a fairly good-hearted person but spiteful with a quick fuse, reserved and repressed and unable to keep a straight face, and so on. Might be a goofy example, but the culmination of having seen her from so many sides is that when she says her dream to be ruling the world, it's so recognizably like her. A line like that is easily perceived as cringe or even out of place, but I appreciate the manga's willingness to take it seriously when a character says or does something conventionally weird. As a side-note, this manga brings up a lot of interesting or informative things which wouldn't be expected in a romcom.
Also, the story doesn't hold back on committing to characterization even if it can make them less likable on a personal level. Kaguya relapsing into IceGuya after the high of the confession and hurting Shirogane is what works from a character perspective, but it made her less likable and I think was kind of a daring storytelling decision.

The relationships.

Which characters intersect with each other is not frozen in place, so as the story progresses, characters meet and new dynamics form. Miyuki and Hayasaka becoming friends and having such joint development, the trio of Miyuki, Ishigami, Maki becoming so prevalent, Osaragi and Kaguya having that conversation about Miko, etc are all things the reader has no reason to expect, but the story goes there. The amount of combinations with a developed dynamic is incredible. While the character relationship charts define them in very simplistic terms, that's definitely for humour.

The atmosphere.

I've seen the short-lasting alterations in atmosphere be a complaint for some: the School Trip and the War arc as the main recipients. In my mind, this comes down to the series not being a stickler for genre as opposed to a flaw, and the fact that they're in place in the story as Shinomiya family is established a looming presence from the outset.
Another facet of the atmosphere is the flow of time. Quite a bit of the story happens off-screen: a six month time-skip in the first chapter, Ishigami falling for Tsubame, a lot of the lead-up in the war arc, etc - coming down to even a small scale between chapters, which creates the understanding that beyond what's shown to the reader, stuff is still happening in the Kaguya-sama world. The existence of Akaverse with Oshi no Ko and Renai Daikou especially reinforces it, too.
Personally, I feel like the years in the story are equally stuffed as they are in the real world.

Conclusion.

In writing, there aren't any absolute truths or rules, because they're like guidelines. Essentially any concept is conceivably used well in the right context. One of these bits of common sense about writing is to be aware of the genre of story that you're writing as it can serve as the frame to keep ambitions in check.
Kaguya ostensibly does know its genre, referring to itself as one. But in having meta comics about the "Love is War" part of the story being dead, it signals the flexibility it has in defining itself. It's not a revolutionary series, but it's unruly in how it does stuff.
In terms of practicality, every story has a boundary which it won't cross because of prudence, knowing it would dilute the central story or overcomplicate it. If you think of something likely to be outside of a story's boundary, it usually feels obvious that what you're thinking of is unimaginable in the specific story. For example, some of the fucked up things in Berserk are fortunately completely off-limits in Kaguya-sama. It's not a shortcoming to set a boundary for a story, it's simply practical. If a third impact for stories eroded all barriers between every story ever written, I can't imagine what the watch order for the series soup would look like.
But in terms of Kaguya, the first limit for it is Aka's individual scope for imagination, rather than its genre, I think, and considering Aka appears to be a very well read and thoughtful person, it's more than enough.
The biggest example is the very premise of the series, initially the core focus which can't possibly be resolved before the ending as there would be no story left, being resolved before the ending, around half way through the manga. I'm glad it didn't end with the confession because it got to explore its characters and themes and the main relationship much deeper. Had this series ended with the confession, it would still be a fantastic romance story, but I don't think it'd have such a strong identity or world.
I do have issues with the story, too, like Aka post chapter 235 leaving things unfinished and rushing the War arc, both in how the arc unfolds and the emotional responses of the StuCo. Yet it's not badly written at any point, nor close to toppling the series, for me.

Kaguya-sama has made me reflect on things in a way other stories haven't and I think it did impact me as a person significantly. A stretch of 2020-2022 is in part summarized by obsession with the series for me. I know other people for whom it is the same, but a very different experience. There's a split in readers whether they read Kaguya or Miyuki as the main main character, for example. And a lot of the people with an equally powerful attachment to the series would shake their head at my alluding to the School Trip arc being part of peak.
I hope this essay touches a shared point in what makes the story what it is for its fans
in truth, I'd love this essay to go into diegetic analysis of the characters and story as well, but I don't know how even to approach that without leaving it half-baked. So mayhaps this meta analysis makes for a good boundary for this.

In the first version of this essay this line said "Kaguya-sama is simply whole." Not wrong, but I miss the enthusiasm with which I wrote it.
Also, Hayasaka best girl.