山彦 The wilds of Japan are full of strange phenomena, like echoes that bounce back with more delay than they should, or that come back slightly different from the original sound. When the false echo comes from the forest, it is usually attributed to a ko-dama. When it comes from the mountains, it is due to something called a yamabiko. They are very small, appearing like a cross between a dog and a wild monkey. Yamabiko are known almost exclusively by their voices alone, which are skilled at mimicking any sound, including natural sounds, human language, and more recently, trains and cars. They also occasionally unleash terrible and mysterious screams deep in the forests that can carry for very long distances. Little is known about these yokai due to their rarity and elusiveness. They live deep in the mountains and make their homes in camphor trees, living in close proximity to (and sharing a common ancestry with) the other tree and mountain spirits. For many centuries their calls were speculated to be a kind of rare bird, other kinds of yokai, or even natural phenomena. It wasn’t until the Edo period when determined yokai researchers like Sawaki Sūshi and Toriyama Sekien were able to confirm the creature’s existence and record its true shape.