We all know that the Japanese can be weird sometimes. Really weird. Well, it turns out that their craziness is not a modern phenomenon - it’s been around since at least the feudal period! Consider this: the Kage-e or shadow pictures, a popular form of woodblock print from the Edo period.
These pictures consist of two parts: a “shadow” image and a “real” image. The shadow image, which typically bears the shape of a common, easily identifiable object, is viewed first. The real image, viewed second, reveals the surprising true identity of the shadow.
The kage-e above is by ukiyoe master Kuniyoshi (ca. 1852). The shadow looks like goldfish, but it’s actually flying tanuki (raccoon dog) crushing a man with its giant testicles!
Pink Tentacles blog has more: Link