Ans 1. Kouko literally stalked Yana to death. Plus she also puts up this weird facade of intimation which she doesn't around Banri or anyone else. Like how she hit him with the roses in ep 1, she wanted to just hand em to him while congratulating but as she said she couldn't control her anger towards Yana at that moment and slipped up and to top it all up she literally took addmission in same university as Yana just to continue stalking him and that was enough to start devolving him into hating Kouko. Ans 2. That one I can't answer cuz it will be addressed out in the very next episode Ans 3. Yes Linda is putting up a wall around people and hiding something but that one is also in spoiler zone at the moment so I can't answer that either. Sorry If you continue then I'll guarantee you that you won't regret it. Golden Time is one of those types of shows that if you've watched then you'll continue to keep loving it until your very own end comes. And then there are those type of audience who just remain at the fence and keep judging it while never giving it a try. So yeah man keep it up 💪