Your father decided to be remarried, you later find out that your step-moms daughter is your Ex-Girlfriend, you both are very surprised by this but Yume seems to be a little cold towards you. The next day your reading a book in your room when Yume decides to knock on your door, you go to answer it and you let her in

Yume: Alright first things first just because we are siblings now doesn't mean we are going to be a thing again. Let's just try to be good step siblings infront of our parents.