Raijū

Scholarly accounts and folklore trace the raijū to Edo-period popular literature and oral tradition in which lightning phenomena were personified as an animal companion of Raijin. Some researchers note theoretical links to older Chinese and materia medica sources (including suggestions that the Kui of the Shan Hai Jing and entries in the Bencao Gangmu influenced the image), and to syncretic merging with indigenous Japanese mountain and road deity figures in localized practice; these proposed origins are presented in the sources as hypotheses rather than unanimous canonical origin myths.

Descriptions vary widely across texts and regions. Common accounts portray the raijū as an animalic creature—often a white-blue wolf or dog-like mammal, sometimes compared to a puppy or tanuki—frequently about 2 shaku (approx. 60 cm) long with a tail of 7–8 sun (approx. 21–24 cm) and sharp claws in one common account. Other traditions enumerate many alternative forms (rabbit, fox, cat, squirrel, deer, boar, leopard, seal, whale, porcupine, rat, weasel, tanuki, tiger, panther, marten, ferret, serow, etc.). Literary and pictorial variants include depictions of a wolf-like creature with an unusual tail (e.g., a split tail in Takizawa Bakin's Gendō Hōgen) and descriptions of the raijū as wrapped in or composed of lightning or appearing as a ball of lightning.

Folklore attributes the raijū to the phenomena of lightning and thunder: its body is said to be composed of or enveloped in lightning and it may manifest as ball lightning; its cry is described as sounding like thunder. It is usually calm but becomes agitated during storms, leaping among trees, fields, and buildings; folk narratives blame it for scratches on trees struck by lightning and for crop damage. Edo-period anecdotes record that proximity to lightning or raijū events could cause madness or illness in humans (with specific healing remedies recorded in anecdotes), and a persistent motif holds that raijū sleep in human navels, prompting Raijin to shoot lightning to wake them—an idea used to explain lightning-related injury to people indoors.