Been a while since I read CwM, remind me why Kyouko is specifically slutty in comparison to his other FMCs?
She is quite the only FMC on the his games that don't actually needs to be corrupted. Is very noticeable that she knews Kengo intentions from the start: the constant praising that she received from him since they started the trail and the flirting way that she used to answer them in a certain flirty way that only got more blatant with alcohol, the way she blushed when he positioned himself behind her when setting up the tent, she even blushed at that moment but didn't do anything to stop him. I may be wrong, but i also remember the MC or her saying that she was kinds of a whore or a "party girl" on her teenager years. She also didn't had any reluctancy when it came to continue letting Kengo fucked her, hell, she even started a relationship with that mf and tells you in a way thar shows that she didn't though TWICE about it.
At least you get to fuck Kengo mom, which also makes me heavily suspect that Kyouko talked her into it, since if you look closely to her dialogue, Kengo mom tells you she is already being eyeing you for quite some time and noticed already the way you looked at her. This part of her dialogue is also what makes me believe even more Kyouko knews Kengo intentions since BEFORE the trip and already had the possibility of doing that in her mind.
It's also impossible for us to deny that she also knews that Kengo would send those videos for her son, she already knews the proximity that they both had since the MC knews Kengo story's veracity from the school, and with the way he showed himself around the campfire makes it kinda obvious that he would eventually do that to show himself.
You can look at every single FMC of his games, even the one from rural coming 2 needed some influence to get corrupted by the uncle or by the husband to start the swing, but Kyouko is the only one who knew from the start who clearly knew the antagonists intentions and had gone for It without thinking twice. Azusa did for Pitty, but Kyouko did it for lust, and even tho she still a better mom than Azusa.