Just finished my first play of this game (got ending 2), and I really loved it.
I didn't think much of the way the choices are managed, the situation of only being a guidance is not new for me as I spend my free time often searching for hidden gems (or just hidden weird things), but it still really surprised me by how it was handled in that visual novel.
So often in choice based games, you decide of a way to be at the begining or as the story unfolds, more or less limited by the personality of character you control, which restricts your options in a way that feels natural if well done.
Thing is, often those games where you are just a guide, well you are not limited, you are you and the only limit is how the character you follow will have a different opinion, but often will stick to your decision (implicitely the role you have in all visual novels then).
And having both at once with a guide who is a character on its own with a clear personality, resulted in something I never expected would happen : I would make choices that are the opposite of the way I decided to be, just because reverse psychology would realistically work to reach my goal.
The real twist is not the concept, it's to take that concept seriously and to the end will all that entails, I can't wait to see how it is when I'll play the game again with different choices, I have a feeling that trying to reach a bad ending will include a whole bunch of manipulation I am not used to in a visual novel (aside from those of investigation but we see less the emotional side of it).