Hello, I like this game, it feels very well made and the only "complaint" that I have isn't that big into the gameplay, just that I would like other fetishes to be used as attacks.
In example, I know not many women are into feet but it would be nice to be able to counter feet attacks (like a skill or perk to sensitize feet to create recoil) or have a skill to be dominate that could lead to either a stun or stop an attack related to it (like if Shizu is using her Bowing the Mountain skill, you can turn the tables on her) because not all feet related stuff is about being dominated.
Also, this idea came to me recently, that the player should learn hypnosis (at least as an upgrade from sleep, because sapping 10 energy per turn isn't that much of that help in general) and while I don't know which characters you think it would be better used, I would like to suggest it with Beris, since she is into submission, it would be an interesting romance/relationship if one could hypnotize her to be even more submissive and, depending on how you handle that, it may lead the character to be in problems (or in better relationship) with the other sisters.
I don't plan to say everything coming to my mind of what it could be done, since one thing is the idea and another its implementation, but it makes sense that Beris would be the easiest one to hypnotize and submit, considering she is into that.
Thanks for reading, have a nice day.