ooo this might get long mainly bc my hcs are pretty fluid but for me personally:

haruka - gives me major he/they vibes. like i don't think he'd put a label to it at all. ditto to sexuality really, like he gives me the vibes of rolling w/ w/e
yuno - transgirl yuno... i like that idea a lot... for me she's either bi or straight
fuuta - when i'm rotating him in my head he's just a regular cishet dude with minor mental issues because i guess that's what my stupid ass needs. i also like transman fuuta... i think he could be bi too
muu - i like to project my own cis biness on her LOL she's a bi femcel to me
shidou - no universe where he's cis i fear. thanks to my oomfs i just play with him like play dough when it comes to ships so like i think he is literally whatever sexuality i feel like in the moment
mahiru - pan or comphet lesbian imo. i actually don't have a specific gender hc for her. her gender is big boobs and fat ass
kazui - to be honest. his fucking trial 1 mv has left me completely clueless so i just shelve him in the back of my head. is he straight. is he gay. did he have a wife. did he cheat. tbh i don't know so he's on the shelf
amane - i fucking LOVE the amane transitioning when she's older hc. shidou not recognising him. good stuff. no specific sexuality hc i think there's a bit too much cult dedication going on to even think abt sex
mikoto - 0909 is so real and canon and in this essay i will- anyway i personally see him as bi or pan, trans too tbh
kotoko - that cis turbolesbian with the giantest fucking strap yep

anyway sorry this are so boring. took a while bc i don't really think abt them too much HAHA every day all i do is just rotate fuuta in my head. maybe give him a shake from time to time