So a couple of things got me feeling weird about this Manga (like it's general direction and plot).
I think you may be overthinking the manga.
1) Sure, it's in the title, but I don't think the "debut" was ever going to be the central point of the manga. There's no time travel shenanigans, we're past the first day. I see it more about adjusting to school post-debut. And clearly both leads have their issues to overcome. I don't consider it a failure for Kusonoki to realize she doesn't want to rush making a ton of friends, it's just one step in learning to understand what she really wants (which we don't really know quite yet. we are only 6 chapters in after all).
2) I'm guess we're going to learn more overtime? You're right, we don't know much, only got a few glimpses of keisuke's past. Hebikawa apparenty scarred him and he blames her for the bullying he got in middle school. But this is in his perspective and we've already seen he's an unreliable narrator. In Keisuke's eyes he sees her as this intimidating, manipulative figure. But in terms of actions, We have zero information of currenty day Hebiawa. She bumped into Keisuke twice and he went to the nurses office due to his own mental trauma. And now she... came in late to gym class. Menacing.
I'm guessing this dodgeball arc will be a chance to learn more about their relationship.
but the extent of power he gives her and some off hand insult he wasn't even supposed to hear is insane to me.
High schoolers be dramatic like that. That's nothing special lol. I unfortunately still remember some insults hurled indirecly at me at that age. It's just rough as you're still in a phase where you're learning who you are and what you want in life.
