The incessant toilet-breaks is yet another terminal-illness death flag... but it would also be inconsistent as it didnt happen at the library and this activity wasn't much more strenuous. Feels like the author is spamming so many terminal-illness death flags that it is either not going to happen, or mc is going to be the one dying, as a "twist".
Since she knew of her past (and address, etc.), I assume she is the little sister (because she is so tiny mc looks like a levitating ghost on some panels) of the friend she bullied into suicide (no clue how they are in same year. maybe she was held back from locking herself in her room for some while? Or lil sis did something to get elevated? Or the ages aren't that apart and she simply is tiny for her age?), either wanting a convoluted revenge, or feeling like it wasn't actually her fault and saw her ruin her life with guilt she wants to help fix. With the symbolism of the morningglory, I assume its at least not revenge (they might symbolize the love the theorized dead sister held for mc instead tho, expressed in a theorized novel. Would also explain why she would keep on having flashbacks to "disgusting" relating to writing novels, with her rejection being joining in on or even starting bullying when said novel was found).
But at this point I have taken over 3 leaps of logic, running fairly solidly in farfetch'd territories. Doesn't stop me from making another leap tho, and that to avoid the terminal-illness death flag this will end with mc's suicide to uphold the narrators prophecy of it being the "first&last summer", this piece of narration looping back into a novel of their love which serves as her suicide note.
On a more grounded level tho, I think the death flags will remain true despite being
too prevalent, and that much of that above speculation is incorrect. Solely because the girl spends too much money without seemingly any restraint whatsoever, which only ever makes sense if she truly expects to die that soon.
I do prefer the more farfetched interpretation tho
@Shintaro_71 while it might be possible for ppl irl (such as for me) to entirely not recognize ppl after years has passed, I really doubt that is the case here, in manga world, where such a thing would break immersion for too many people.
@WhereTheYuriAt @Bistai I find that with the way the story flows, there is a very high chance said "bullying" was so traumatic for her because the victim took her life. Like in ch1, she said her novels themes were "empathy, sexism, shame, death", which sounds like a strong indication of bullying a lesbian girl into suicide. Unsure how empathy joins in there, but mostly because I can imagine too many interesting ways.
So no, even if the bullying actually was somewhat tame and "for understandable reasons", if my guesses are anywhere near the correct ballparks, I can see why mc's character might be envisioned the way she is without being deflated just because she didn't actually
want to hurt the kid or do anything more that say words and/or reject/ignore her.
All that said, considering it happened in elementary school, my guesses are probably extremely off in the entirely wrong ballparks (iirc elementary school is pre-puberty).