Raijū

In Japanese mythology, the raijū (雷獣, らいじゅう) is a legendary creature associated with lightning and thunder, as well as the god Raijin.

Mythology
A raijū ' s body is composed of (or wrapped in) lightning and commonly conceived of as taking the form of a white-blue wolf or dog, among other such animal forms as a tanuki, leopard, fox, weasel, black or white panther, serow, ferret, marten, tiger, and cat. It may also fly about as a ball of lightning (in fact, the creature may be an attempt to explain the phenomenon of lightning, such as ball lightning). Its cry sounds like thunder.

Raijū is the companion of Raijin, the Shinto god of lightning. While the beast is generally calm and harmless, during thunderstorms it becomes agitated, and leaps about in trees, fields, and even buildings (trees that have been struck by lightning are said to have been scratched by raijū ' s claws).

Another of raijū ' s peculiar behaviors is sleeping in human navels. This prompts the Raijin to shoot lightning arrows at raijū to wake the creature up, and thus harms the person in whose belly the demon is resting. Superstitious people therefore often sleep on their stomachs during bad weather, but other legends say that raijū will only hide in the navels of people who sleep outdoors.

Origin
It is believed that the myth of raijū originated from the Chinese materia medica text Bencao Gangmu. Scholars believe that there were raijū sightings and documentation during the Edo period in the history of Japan. However, it is also believed that sky being an unexplored territory in and western scientific and technological knowledge had not reached Japan, the mysterious phenomenon of thunder and lightning were attributed to the notoriety of raijū.

Raijū are given negative connotations as many things were happening in the sky, beyond human beings of Edo period's reach. While the depths of oceans were also inaccessible to human reason, oceans were helping humans with fishes (food) and sustained life forms. In this sense, phenomena of the sky were transcendental and given negative connotations to the phenomena and the creature.

Scientific attempts
Dead animals were found from under trees after a stormy night in Japan. Attempts were made to debunk this myth. It was claimed that dead raijū are essentially real dead animals startled or knocked off from the tree during tempestuous weather of Japan. Recent theory suggests that raijū are essentially a small tree-dwelling creature called hakubishin (Paguma larvata) found in East Asian countries such as China and Taiwan. While, some scholar believe that Paguma larvata was brought by soldiers of World War II as pets, the bearish resemblance of raijū in paintings from Edo period also suggest that Paguma larvata (Masked palm civet) have been in Japan since much earlier. The gem-faced civet has also been considered the inspiration for legends of the kuda-gitsune.