I think it might be amusing to have futa protagonist be a were-futa just recently started having her clit turn to a cock. Or maybe just recently became regular futa. I'm trying to leave a grab-bag of ideas, or at least the skeleton of one to be fleshed out.
As an aside, it flows very nicely into having a character like:
>>60642
Though besides having a lot of scenario-characters that themselves are designed with sex in mind, if you start with some kind of futa-curse, you could have that push sex into the scenario.
Maybe some kind of "speaking withing earshot of an aesopist genie" thing, where regular girl complains how it's so hard to get noticed and wishes she was a guy so it's not weird for her to approach romantic prospects. Then some kind of sadistic witch gives her a cock, makes her bi, and turns her sex drive up to 11.
You could have story branches where you choose whether she tries to pass herself off as a guy or not, leading either to failure, success, or maybe just to differing sex scenes with the same character. Come to think of it, this can work for regular futa as well.
And one more potential thing is for the good ending the player has to successfully make all the dates lead naturally to sex, or maybe the overpowering sex drive results in protagonist raping the target.