Be reborn as a young man and make all different choices this time.  This harem story has a somewhat distopian plot; a lot of depressing things can happen.  Choices do matter; you can't get all the girls in any one playthrough.  The sandbox is implemented in a way that events don't fail to trigger, though it is not always obvious what you need to do next.  I haven't been able to find a guide or walkthrough for this even though it is big enough to benefit from one.