The biggest sin one could do is to not crossdressing ofcreally like the extra illustration of her and Ui's angel/devil counterparts. I wonder why Ui's devil is the one that isn't crossdressing...?
Having a kink is normal and okay. Be yourself and exercise your kink in a safe way with other consenting adults if necessary!I can relate to not being able to kick a kink. It sucks since you're just kinda stuck with it. Hopefully Ui forgives her for being a degenerate.