Uh, either my eyes are in the wrong sockets, or these images are reversed. If you cross your eyes hard enough so these images match up, they should be 3d. I flipped them around in an image editor and it worked. Pretty cool, really.

虹符「アンブレラサイクロン」
Rainbow Sign "Umbrella Cyclone"

毒爪「死なない殺人鬼」
Poison Nail "Undead Murderer"

I’m not sure what the exact term is, but I usually call these “reverse” stereograms. They look inverted using the normal method, but if you cross your eyes the other way, it pops ‘out’ instead of in. And I don’t just mean that it fixes the view, normal stereograms go into the page/screen and then pop up... but these float above/out-of the page/screen. They are also harder to do sometimes...