Technically, yes. You choose one of the two girls and make interactions as if you are taking on their role. Although it always seemed to me that the player in my games is rather an invisible spectator who has some ability to see further and influence some events, trying on different roles. In the end, in this particular game, the main protagonist may turn out to be boys assistants or a professor acting as an examiner and choosing tests for girls. In short, choose what you like.