I can vouch that people this naive from being sheltered really do exist.
I have known sheltered people who would absolutely be this gullible in the most unexpected of ways.
Like, a grown adult who's gone to public school with everyone else, but was then shocked years later to find out that people save and eat left-overs and wear the same clothes more than once. You'd be surprised at what some people don't realize simply by virtue of having never entertained the thought.
I don't get where people are getting the transsexual angle from. Other than being an androgynous-looking lesbian who's stuck "having to" crossdress for her girlfriend, there's literally nothing about her that implies a transsexual leaning. Personally I'm really loving every chapter of this. If this was real life I'd be worried about the train building momentum for an eventual crash, but seeing as this is a fictional narrative written for yuri fans, I'm 100% sure things will work out just fine.