The intro scene was wonderfully sweet. The language portrays emotions that contrast greatly with the time skip to the present day. Your use of descriptions leave just enough for the imagination of the reader without leaving a blank or poorly described scene.

The prose reminds me a lot of Nabokov's; Descriptive but not verbose, blunt but not vapid. In fact, it's as if there' a bite of magic in every word.

One aspect I think could improve is the use of a thesaurus. My autism picked up when you repeated a word too soon.

My only real gripe with it is a nitpick, and it's that the paragraphs are all squished together. Blank lines save eyes! This issue only becomes worse in the moments that Anon begins daydreaming. There's no line that separates one event from the others and it becomes an eyesore.

Adding links to what is essentially the fic's soundtrack was a surprise. It's right up your autism alley considering all the material you made for Holoslavia and personally I think it's a fun flavor to add to the fic. I myself would probably just reference a song or lyrics, but adding a link gives an extra step for immersion.

As for the story itself.

I like how you introduced the vtuber concept by essentially making the chuubas regular people donning costumes.

How you managed to blend in the actual "The First Take" session and give it such a profound meaning was outstanding. I love how you merged the real world with fiction so seamlessly.

Adding real brand names in a story gives a sense of tangibility to it, if that makes sense. It feels closer to what one lives and makes it more mysterious when it's something you don't know, like american candies are to me. Hell, I ever find myself in Japan, I might want to try a packet of cigarettes because of this fic.
The motif with astrology was a nice tie-together, and it warmed my heart to see it.

As for the bond between Anon and Suisei, I beleeb it. You sold their relationship naturally, but Anon's doubt was dull. The moment they start writing to each other, Anon goes "Wait, is this right? Am I a siscon degenerate?" Out of nowhere. Sure, he already was, but everything he had to really stop and wonder was a kiss, and a fairly innocent one. -At least, that's all that you showed us-

Same for the reencounter, things escalate to incest a tad too fast. A bit of backstory where maybe, I don't know, the two just really each other as a couple (I mean aside the umbrella bit) or maybe some pubescent curiosity getting the best of them could've added to the spice, otherwise, the fic could've benefited from a section from Suichan's point of view in which we learn of her incestuous desires beforehand. Makes the reveal land better, specially with how casual Anon was about it at first.

The smut was poor. A scene doesn't necessarily need to be long to be sexy, although that depends if you're going to leave things to the imagination of the reader or if you want to make full wank material. If you're not committing to the latter, I suggest a couple of lines and then a nice fade to black. The cumming bit thought- Taste of copper? Magnificent.

The prose didn't falter, but the scene fell a bit flat. Poorly paced, but hey, I've been there too.

The problem of pacing carried itself over with the bits of drama between A-chan, Sora and Yagoo. She's in love with Anon, and we just learn of it because of her snitching on the Purest Form of Love. The only real solution I could think of this was, again, to have segments that didn't include Anon, or -very well- that gave us a little foreshadowing about the nature of A-chan.

For the climax, you didn't fully commit to the idea of murderer A-chan and Yagoo felt out of place with the blackmail he was bringing in. The tie ins to the legal aspect was well written however. The bittersweet feeling could've landed a bit better with some more setup.

That's overall the only problem the fic really has. The scenes are there, but they needed a bit more substance before they truly came together for the angle that you went with.

I read the notes at the end and some of your explanations in the other posts for stuff that I already mentioned to which I say; I understand. It's not right, but I understand. It hurts to see your oshi crumble and fall, but sometimes, tragedy is the only outcome that follows a story of repressed joys.

Look at it this way. You have to respect your story, and accept that sometimes the ending that must be written isn't the one you want. After all, when you start writing a story, it's like seeing a kid grow, isn't it? You might not know where they might end up, but you can't hold their hand forever.

Here's some excerpts that I found outstanding, and memey.

an individual with whom you could express your emotions with absolute precision and depth. It was an invaluable gift that most people could spend their lives looking for, but never find.
Seeing her like that carved an ache in my heart so deep that only one thing seemed capable of filling it: pulling her close to me. To keep her in my arms. Forever, if I could.
“I often catch myself staring at the stars late at night, wondering if you're looking up at them too,”

I love how simple this line is both in wording and prose, but how much of a punch it packs

did nothing but reinforce the notion that my memories of this city were tinted Rose, only made colorful by the woman right next to me.
She might as well had been shedding the sorrow of a hundred years. And I would’ve shed them with her.
Suisei retorted, her voice tight with focus as she applied more povidone-iodine onto the fresh wounds on my back.

Mm-mm! Love me some love marks. If it doesn't hurt, it's not love.

“then let’s be guilty together.”

Delicious.

Through thick and thin, my sister and I were inseparable - comrades-in-arms

Holy shit Holoslavia refenrence?!?!

I was lost and found all at once.

Oh I hate you, this sounds like a title drop for that other fic and I had a fucking coughing fit when I read it. Now all this this fic needed was a fucking title dro-

So that’s when I began having an egregiously forbidden relationship with my younger sister, who turned out to be the internet idol Hoshimachi Suisei™.

I'M GOING TO FUCKING KILL YOU

The greatest praise I can give this fic, is that I'm jealous of your writing. I compare it to mine and feel so irredeemably mogged that I will now delete all my fics and commit honorable seppuku through disembowelment.

You're obviously very talented or at the very least extremely dedicated to your craft and it shows. Pumping out this behemoth of a fic in such a short amount of time is no small feat, for so much of it to read so effortlessly written, I really envy you.

If this works as a frame of reference for anything of this sort you'll write in the future, I can surely say that you will kill it.