A fisherman sits by a river on a warm night. Something bobs near the bank — a small shape in a kimono, like a wooden doll set adrift. He leans closer. The doll's face splits into a grin and giggles.

That's how you meet the enkō. A Japanese river yōkai that looks like a monkey-child and can rip the liver from a living body with one impossibly long arm.

But here's the strange part — sometimes you can defeat it with a polite bow.

The full story of this creature is one of the most disturbing and fascinating I've covered yet.