The ōnyūdō (lit. "large monk") appears in numerous Japanese folk tales.
Onyūdō appearance varies from story to story, but he is always big, ranging anywhere from 2 meters (6 ft 6 in) tall to as large as a mountain. Some stories describe him as a fox or tanuki (raccoon dog) that has shape-shifted, but in most stories his true identity is a mystery.
In most cases, the ōnyūdō is a malevolent figure that can cause people to fall ill simply by looking at them.