Have you ever wished your dog could talk to you? Well, why don't you go and get yourself a Jinmenken? They are dogs with the face of a human. They've been reported in Japanese cities, or running alongside highways at supersonic speeds.
Unlike other creepy Japanese creatures, the Jinmenken are harmless enough. If you leave them alone, they'll likely ignore you. If they do speak to you, it will generally be to insult you. But what are they? Scientific experiments gone wrong and escaped from a secret underground lab? Trapped souls of car crash victims?
The least freaky theory is probably the best. According to this theory,Jinmenken are actually Japanese macaques, who have dog-like fur and human-like faces. It isn't hard to imagine that, should someone see a macaque after a heavy night out on the town, they could confuse it with a human-faced dog. ("Pour me another sake, bartender. I'm seeing dogs with human faces!")