The high school you're going to has an interesting use of the gender swapping procedure. To try and counterbalance the effect of puberty on students, your new school practices a system called 'inversion'. Simply put, what inversion involves is transforming everyone's sex to its opposite, and allowing pubescent development to proceed in the new gender.
As a result, everybody going to your new school is faced with the fact that once they arrive, they won't be the same person again. Boys will have to get used to being girls, and girls will have to get used to being boys. A few people are super excited about that, most are downright terrified. To most people your age, the prospect of losing your cock or your tits, having everyone treat you different and your whole body feel totally different are intimidating to say the least. But it's what will happen, and you all have to learn to live with it. Besides, once you go off to college, you can switch back if you like.
But about you. Today is the first day of term at your high school, and you're gonna get changed once you get there. Tell me what gender you are right now, and how you feel about all this...