A young guy has a twin sister. Normally when twins are a boy and girl they aren't identical. This time he is identical to his sister except for the female parts. So he decides he want's to become a girl at least in part. He starts with breast implants. He does everything to make sure his boobs look exactly like his sister's. In the process of looking for the best place to make his lower half female. He finds a mysterious place and is weary about going there. But for some reason he ends up going there. Soon he is now identical to his sister in every single way except for maybe fingerprints. He is really excited at first and yes part of him misses his old self especially his dick. Eventually he finds out that he is even more like his twin sister than he thought. He is now 100% female even the DNA work shows he is woman. He can even have babies if he wishes.