Board Thread:Theories Discussion/@comment-27012505-20150923180253/@comment-6192846-20150923191112

You forgot the black box that embodies the inner psychological world/Court, the black box Kyle finds himself in during his "dream" of Ney/Banica, Black Box which Sickle has as his multi-purpose device, and Black Box Type S which Seth uses to draw people into someone's inner psychological world.

The significant of all the black boxes we see thrown around this series aren't explained so they're naturally looking like mostly random and ridiculously coincidental choices. There're probably more rules to the universe and mechanical reasons behind why they keep cropping up, maybe a few even being the same exact box.