You'd think after seeing that it's Otone who keeps advancing the relationship on her own initiative (she brought up the subject of romance, cutely needled Onee-san for whom she was in love with, asked Onee-san for them to be lovers, asked to touch Onee-san's breasts, and offered to let Onee-san touch her body in return when Onee-san didn't even give a hint that she was expecting/wanting anything) that people would seriously question whether "grooming" is applicable here. If anyone is doing any "grooming", it's Otone that is "grooming" herself on her own, with Onee-san having little to no input in the matter (she's not even responsible for the "grooming" being started to begin with!).
In fact, what we should be questioning is the following facts about this world that we've learned from Chapter 4:
* Exhibit A: It's quite normal for a periodical magazine to discuss "love among elementary school students" and do a survey on whether said children are "going out with someone right now", 20% of elementary school-age children answered said quesiton with "Yes", Otone merely commented that she finds the magazine's material too complicated for her to bother with, while Onee-san merely commented that "today's kids are quite precocious".
* Exhibit B: Otone, a third-grade elementary school student, already knows about homosexuality due to having been taught that in "ethics class". Keep in mind that the story is set in Japan, which is not known for being progressive on the subject of LGBTQ+ matters.
* Exhibit C: Otone is not at all weirded out by Onee-san confessing that the former is whom she's in love with; in fact, she seemed more confused by Onee-san apologizing for being in love with the girl (which is a very good point; she can't decide who she falls in love with, so why feel bad about it?). Apparently, she doesn't seem to even pay much thought to the age gap between the two of them, which implies that there's something quite unusual in her upbringing.
And of course, there's the weirdness that, barring Chapter 0 (which, in hindsight, appears to be more of an independent pilot that was made merely to test the waters, and isn't actually connected to the subsequent chapters continuity-wise), is Otone unilaterally keeping her newfound relationship with Onee-san (which, I must repeat, is Otone's idea) a secret from her parents without any clear in-story reasoning behind it. She clearly thinks little if anything of the age gap, and we've yet to see either her or Onee-san discuss or even allude to the secrecy in any way; the only sign that Otone is even hiding the relationship is when she decided to bathe alone for the first time in her life to avoid having her mother see the hickey on her stomach, and even then, her past behavior makes it quite plausible that she did it merely out of embarrassment over having a hickey than fear of her mother flipping her lid over discovering that someone was physically intimate with her elementary school-aged daughter.
I mean, I love my lolicon manga and doujinshi, but this is the first time I've seen such a story where the couple's secretiveness about their relationship appears to be conspicuously inexplicable by way of lacking an actual motive. Even the Master and Mel manga brought up the illegality of the couple's relationship on account of Mel being both underage and a beastkin (though I'm not sure whether they're separate factors, or inherently interlinked in the "beastkin are permanently stuck in childhood" sense), and how the two's relocation to a remote and smaller country house was entirely for the sake of being able to pursue their relationship in the safety of social isolation from the rest of the world that (at least for the time being) rejects said romance without room for negotiation.
You wouldn't think creepy-cute slice of life would have continuity problems, but it's kinda hard to reconcile chapter 4 with the rest of it?
What continuity problem? And before you answer, you should read Chapter 1, since what was originally listed under that number is actually Chapter 2.
Man whomever wrote the last page of chapter 4 is my spirit animal
Incidentally, it's also the last page of Chapter 1 (the actual Chapter 1, which was uploaded alongside Ch00 and Ch04).