Aight, I read up until your latest chapter. I was genuinely curious to see if you would explore all the ideas and plot threads you set up in the beginning of the story, but I found myself checking out basically by chapter 4.
I thought chapter 2 was kind of a step in the right direction, with its introduction of all these new characters and *gasp* even more plot threads. As I was reading though, I found myself wondering when we're gonna actually learn more about this weird time stopped world and when we're gonna actually learn about these new characters who were introduced just so abruptly, with no real attention given to their personalities or even their appearance. Those thoughts were quickly washed away, however, with an "it was all a dream" bit. Granted, you've followed up that bit with hints of an "...or is it?", but I found myself having trouble caring about those hints because the story just moves at a breakneck pace, without really any sense of causality between what happens in it. In my opinion, a lot of the story up until this point just feels like a lot of "and then", "and then", "and then"'s.
I don't have much to say about chapter 3 except that I noticed a lot more of it reeks of AI generation, but I'll come back to that later. Again, the characters introduced in this chapter all feel like faceless blobs. The dialogue feels like canned anime dialogue, generic and stilted, and I think there's a lot more of it compared to other chapters. Seeing Natsumi's interactions with the other characters made me realize that I really don't care about this guy at all. I don't know nothing about him. He's a chuunibyou, for some reason, I guess, and he's kind of brooding too. But I didn't find anything else to even latch onto. To top it all off, the end of chapter 3 gave me severe whiplash with that weird monologue. It's nothing like what had come before it. The narrative voice is completely different, which I've noticed in places earlier, but this was the most blatant example so far. This is where the stench of AI was most pungent in this chapter (If it's not AI, I give you permission to shoot me in the head execution style if our paths cross somehow). And even if it wasn't AI, again, it just comes out of nowhere and doesn't fit the vibe or Natsumi's narrative voice at all.
Finally, chapter 4 was where I decided that my curiosity over the cocktail of different ideas you've thrown in the opening chapters just wasn't enough to overpower the disconnect I felt towards where the story was going. I won't comment on the song. I'm sure it's heavenly if I heard someone sang it to me. Anyway, it opens again with narration that sounds nothing like what we got previously (the presence of paragraphs just fuels that disconnect and AI suspicion, considering that you've barely been using paragraphs). Then, our protagonist goes into his little song. This is just about where I kinda checked out mentally. There were all these emotional descriptions in the bits of narration between the lyrics, but I just couldn't be invested. This scene seemed to be some sort of emotional climax for Natsumi, but I don't even know this character enough to care. It feels like an unearned payoff, rather than actual catharsis. Unless I missed something in the previous chapters that really gave a lot more insight into Natsumi's character.
I won't pretend I understood what was going on in chapter 5, but that's honestly par for the course (it's to the point that I'm wondering if I'm just horribly misunderstanding something about the story). I thought the ending was pretty neat though. It put that single sentence style to good use.
Overall, I think your story would benefit from slowing down a bit. And there's nothing wrong with feeding the readers little crumbs of what's going on as the story progresses, just so that it doesn't seem like a bunch of random events one after another. Give us some more insights into these characters too, breathe some life into their interactions. And also, cool it with the AI, or shoot me if it isn't.