Are there any fitish involved in this game?
SPOILERS!!!!
Probably,
Musk: at Runan's route, It's basically confirmed that he has a musk fetish, and even asks the player if he's "into musk".
Breeding, Daddy Kink, Age Gap: In Joseph's route, he wants to "breed" the player, he has daddy kink, and it seems he also has age gap kink.
I also think Leo has a Body Worship fetish, and I think in the future Jin may have (or have) Chest worship kink.
Ridge and Koku don't seem to have any fetishes at the moment.