Hmm... If the Princess of CUaLG is the Type-S, which I'm guessing, and given that Sasi's also a princess... Then I'm gonna guess that "high-class" is a quality of S-Types, and so, Sumiko is a Rich Girl. ... Or did we already know that by having seen her room? Which is high-class?
Caught up and Let's Go, gotcha. Assuming it's not one of Belle's batch mates, I think Lucy is the Sasiriko since she's short bossy and has a sweet tooth.
On a note that relates to both works es and Aleph sure do write a lot of stuff about unnatural siblings.
Now stuff about a Certain Droll Hivemind.
As someone who has no experience with the source material. More info as to what's actually going on would have helped the first chapter. What's there is fundamentally an infodump about the fact that Misaka 11111 was told to write a journal. There's no action to hook the reader, and you learn almost nothing about the protagonist.
I think that part of the problem here is you're starting in the middle of a story, usually your stuff starts at the beginning. As an example I knew nothing of
Zero no Tsukaima or Exalted before reading GSItV but had fewer issues jumping in.
Honestly the second chapter made a better starting point. Not only does stuff happen but you get a better idea of who Misaka is in it. Honestly I would have read the story ages ago if you had lead with chapter 2. I tried reading the story when you first started it but the first chapter put me off enough that I didn't continue.
On to the lead, Misaka's a pretty interesting comedic protagonist. Good idea with having guest writers for the diary as Misaka 11111's voice can get a bit stale if you're reading the chapters back to back. Not that the other network members are very different but they switch up the jokes a bit.
You managed to handle the being Misaka is pain thing well without overdoing it sofar. I've felt a lot of sympathy for her so far. From the drenched in rain bits early to the horrors of the Accelerator I've felt for her alot. Pretty good considering I have no prior reason to care for the character.
Her "verbal tic" is quite annoying though, the doubling of "said" type phrases is something my eyes skip about half the time.
This is a problem twice, first it means I'm likely to miss a joke if one is put in that bit. Then, when my eyes don't just slide off it mangles the flow of the sentence. Hopefully she'll cut back as the story goes on.
As to the KSE trio, the opening chapters had me actually rolling my eyes at how close they were to their Trials characterizations.
This got better when I started thinking about the whole story as a Trials re-telling with different source material. It does work remarkably well in that respect. A third tier nameless character (who is a poorly socialized super powered clone) and her three OC friends have slice of life adventures in a weird town. Wackiness ensues.
Eiko's initial tenderness/understanding towards Misaka 11111 was well handled, and helped to start developing her into an actual character with more than one dimension.
She started going from asshole punk roommate to going out of her way to relate to and stick up for the most emotionally vulnerable roomate.
Though you ruined a little bit when Eiko said she knew about the Misaka's gun. That revelation and her in-battle dialogue effectively reduced her back to being just a fighter who found another fighter to relate to. Which is less interesting than what I thought was going on. Though the fact that I even got so invested in my headcanon shows that you're doing well though.
Kyoko and Sumiko desperately need some character development though, I understand it early so far. But they are extremely bland for how much "screen time" they take up. Especially the comments about how much Sumiko shouts, that joke has been beaten near to death already.
Overall I liked it once I got into it, the comedy has had me laughing consistently, and the drama has worked well so far.