I think it was obvious from the very first time you see the game over screen in the original game that the protagonist is a girl. You also get to know H-teacher's and protagonist's name in other endings.
Also, if you look in the game files, you'll find a non-decapitated and non-dismembered sprite of the protagonist in the pose (s)he's in when (s)he gets cut open by Viktor in the game over screen. Can you find it???
