Responses
I think the black side of the paper refers to the front side. It's a bit confusing, since black and shadow belong together. But from the main characters perspective, the front side is the black side, since it's evil. And try to read the green box on this page:
http://www.mangago.me/read-manga/the_moon_at_daybreak/bt/344303/Ch01/3/
I am confused which side is the front side back side thing?