She was kidnapped by someone, She came back after 7 years...It's very vague. In original she runs away through a tunnel and gets into a ghost taxi, after that her messages on the board stop.It was [Kisaragi Station]Nonexistent in this world, a station form different reality...There is more information scattered around the internet!
If you wanna know more you just have to search.What happened to the girl?How did it go again?I wonder if that girl too passed through the barrier...But this isn't Mary's dream right? If Mary doesn't know a way out, then it seems like this isn't going to be easy.The way I came in...I don't think we can use it to go back right now.