> Those dandelions! It must be the work of Yuuka!
... Actually, that's probably not a terrible theory.
> Commit the drawing to memory. We should redraw it when we wake up.
So. I think the idea behind the drawing is that Yukari puts up some sort of gap barrier between the two worlds. Not sure how the wings are connected (unless Sariel is involved) and not sure why one of the worlds have little light beams. Question is, who left it here? Is it Yukari trying to provide a peace offering, or maybe someone's subconscious providing it for us?