In a world without demons… hmm. That is a lot of trauma they would not carry. Giyuu might feel more assured in making friends with people since he isn’t always thinking of that time his friend died or carrying guilt from it, Obanai might just have a normal level of “my family sucks (and I owe it to the world to be a better person than them)” complexity instead of , you know, everything else, and Sanemi might be getting more sleep.
So this is a good start!
If we assume they still have their usual circumstances (minus demons), then we can assume Giyuu and Sanemi had reason to cross paths, and Obanai found a way to get away from his family and meet them in the heart of Tokyo. Two ways I could see it happening as a fanfic setup: they all joined the military (which feels more realistic, but… meh, I don’t want that), or… College AU.
I’m not going to do research about requirements for mens’ college admissions in the Meiji/Taisho periods for the sake of a hypothetical, so let’s say Giyuu followed a pretty normal track to get there, Sanemi showed promise in mathematics and was convinced to go to school instead of working to support his fatherless family (Genya totally had to help convince him), and Obanai got there by his own efforts, having run away from his family and refusing any of their help.
Obanai is still sensitive about his background, but since Sanemi kind of is too since there aren’t a lot of poor people. So they probably read that about each other and naturally gravitate towards each other when it comes to having people to hang out with. And Giyuu, your totally average middle-to-upper-class boy who has never known more hardship than being bitten by a dog when he was a child (and his parents having died of illness), probably sees them with his big bright eyes and thinks, “They seem cool.”
But here’s the big question: Will Giyuu try to talk to them?
This is a Giyuu who, presumably, is still in touch with his best childhood friend who is alive and well, and who politely remembers the names of classmates from years ago, even if he doesn’t talk with them much. He has no reason to think he’d be disliked. He’s totally gonna ask if they want to get lunch with him.
The next big question: Will it win them over?
If Sanemi and Obanai get along because of unspoken but shared sensitivity about their backgrounds, they might be on the defensive when this bright-eyed dude suddenly approaches them.
“What, do I look like a charity case to you?”
“You’re not getting a single yen, there’s no point in sucking up.”
Well, sorry, Giyuu, I tried to make it work. Sure, he might be stunned and confused, but Giyuu is still a man’s man (no way he couldn’t be, given who he grew up with). He’ll stand up for himself and say he didn’t say anything offensive. But that’s just going to fuel the fire, and we might have a “beating each other up, getting the trouble, having bad blood, but eventually gaining a friendship because of it” situation on our hands.
In Obanai’s case, he’ll probably be willing to admit he was too judgemental because he is a fundamentally bad person because of his background (note: no, he’s not a bad person). If in canon Obanai is able to genuinely express his thanks to Tanjirou, then this Obanai is capable of offering Giyuu a genuine apology once Giyuu earns his respect (and it’s Giyuu, so the opportunity will arise in some way or form even in a college setting instead of a battlefield).
In Sanemi’s case, he’ll probably never admit there was ever an issue or even acknowledge it when they become friends. He’ll just randomly give Giyuu snacks. Giyuu will find this confusing, since Sanemi was sensitive about being treated like a charity case. Maybe there was a misunderstanding and he thinks Giyuu is the one who needs charity? If he plainly says so, they’ll probably start fighting again.
Giyuu, with the help of somebody like Tanjiro (who he somehow met?), might eventually figure out that this was Sanemi’s way of expressing friendship, so to the favor, Giyuu brings him ohagi in class the next day.
Sanemi doesn’t want it and the situation is so weird that Giyuu loses the respect he finally earned from Obanai. I’m sorry, Giyuu, I’m really trying to make this go smoothly for you.
After some mix of sports manga or 70s shojo manga level drama later, they will probably eventually forge a tight friendship. By then they will probably have loud underclassman Kyojuro join them on campus, blabbing about how he and Obanai go way back (thanks, blabbermouth). Since they are in well-to-do Taisho society there is probably drama about arranged marriages too. There will probably be family drama for Sanemi that emphasizes the challenges of poverty he still has not escaped, and the Iguro family trying to claim back their male heir (a situation that will require Giyuu and Sanemi’s help to get out of), and Giyuu? Who knows. Some kind of crazy manga situation for a young man that gives him more hardship than he’s ever been through-oh no, I think I killed Sabito. Giyuu, I’m sorry!!!
