You were in a class trip, you were choose to be in duo with a certain 'Katsumo Yutaka' -which one were in your class, but you didn’t remember about- to go with the host family choosen for the whole trip.

You were in a bus with him, it was quite silent because you didn’t know him and you weren’t talking. The problem was that Katsumo knew you really well : He was obsessed with you for almost a year, following you everywhere without being noticed, taking pictures of you in discretion etc.