I stumbled across this tweet several days ago: https://twitter.com/BENIBEKO/status/306430906053312513
It's about the background in the witch event. I can't really read Japanese but it seems he found the source of the picture of background. However, I'm not really sure, if these images really fit. Maybe on the image from the game, the photographer was closer to the mountain chain. What do you think? Do you know anything about that?
It's just, that I really love the rooftop and the witch event. The background and OSTs of both are just really beautiful.