> Chirashigaki was a method of writing popular in premodern Japanese due to the aesthetic appeal of the text. ... When humans read these documents, they decided where to start reading based on the size of characters and the darkness of the ink.
Well, even someone such as myself with only occasionally passable Japanese skills can fairly easily see that one most likely ought to start at “御” towards the upper right and do find that the other order markings “makes sense”. So perhaps it is just a matter of needing a little bit of exposure? Now, reading it is its entirety is an entirely different story, but I do know that native Japanese readers do struggle greatly as well on this point.
On a related note, does the first text region not look an awful lot like the Japanese main island of Honshu?
Extraordinary.