This would be the much more interesting route for the series to take, but i doubt it's gonna happen, which is a shame. If this were a VN i'd be doing snake girl's route from day 1 lmao
I definitely have the "if
I was writing this," plot all fleshed out for at least the next bit, yeah. Not saying it'd be good, or that the average reader would even like it, but -
Keisuke feels like he is being left behind by Kusunoki, which he kicks himself over because her whole goal was "my Debut!" - and it's definitely successful thus far, and he doesn't want to take that away from her just because he likes her and wants more of her to himself.
So, he refrains from asking her to go around the festival, and also from joining her and Irie, and just fades into the background and sulks by himself in self-pity. He gets noticed by Hebikawa, who maybe strikes up a conversation, where she susses out that he's feeling dejected over Kusunoki. Hebikawa clocks this, thinks "oh....I can use
him to strip off
her mask, at last" because I think she suspects that Kusunoki likes Keisuke, without really realizing it herself. So she hangs out with him a bit for the rest of the festival, then parts ways.
Over the next weeks, Kusunoki sees her popularity soar following the festival play performance, and Keisuke slowly fades more and more into the background without her noticing because of all the new people around her all the time. Keisuke starts going home on his own, eating lunch on his own, etc - and Hebikawa moves in, spending time with him, teasing him, working her hooks in and feeding his insecurities and playing to his ego, making him lean on her more and more as his walls come down.
But along the way, Keisuke's general thoughtfulness and earnest demeanor work on Hebikawa as well. She complains about things or lets slip a worry or two, and he genuinely helps her out because that's just how he is, and she starts to fall a bit for him, for real. They spend more time together, maybe further figuring out how to navigate her family situation, working on grades, getting lunch on weekends. Keisuke realizes Hebikawa is actually quite nice once you get past the thorny exterior, and the two grow close. Maybe romantically? Definitely close friendship/confidant-level.
Suddenly, they're out on what might as well be a date--Hebikawa actually dresses up, Keisuke stressed over what to wear, whether to say "you look nice", the usual nonsense. While they're out, maybe he grabs her hand when she trips. And
that is when Mei spots them, and freaks out realizing he hadn't been around Kusunoki for...how long, now????
[[Spoiler alert - Hebikawa sees Mei running off, and infers what's happening, and starts planning for Kusunoki, even as her feelings toward Keisuke have started to shift.]]
So Mei runs to ask Kusunoki about Kuisuke's absense, and that's when she realizes she hasn't seen him for weeks at this point. She remembers that she made him promise her that he wouldn't disappear on her during the Beach Trip, and gets upset, both at him, but possibly at herself for "forgetting my first friend". But when she goes to try and find Keisuke during lunch at school one day....she comes across him and Hebikawa, either alone on a bench outside, or up on the roof - and Hebikawa sees her coming and kisses Keisuke in front of her before he notices Kusunoki is there.
Dunno what would happen at that point, but...to me, that feels like a sufficiently dramatic / "high school romance angst" setup for the end of the current arc, before delving into whatever results from that sequence of events.
- -
Anyway TL;DR I have my own thoughts about how it should go, though I bet I'm in the minority.