thumb|upright|The Raijū as depicted in Ban Kōkē's Kanda-Jihitsu.
thumb|A Raijū depicted under the title "Kaminari" in [[Takehara Shunsen's Ehon Hyaku Monogatari.]]
In Japanese mythology, the is a legendary creature and yōkai associated with lightning and thunder, as well as the god Raijin. It is said to appear with lightning strikes.
Legends of the creature exist throughout Japan, centered primarily in East Japan. Its name appears frequently in Edo period essays and modern folklore materials. The same book contains a story about a person in Akita, Dewa Province, who caught a raijū that came down with thunder, boiled it, and ate it.
The Sengoku period warlord Tachibana Dōsetsu was struck by lightning and became half-paralyzed. However, because he continued to fight while riding in a palanquin and showed demon-like strength, a legend was born that he "became paralyzed when he slashed a raijū" (or the lightning god).
Origins and cultural significance
Since modernization progressed in the Meiji era, the fame of the raijū has declined compared to yōkai and legendary creatures like the kappa or mermaid. However, during the Edo period, the raijū was extremely well known. Because people at the time lacked aviation technology, the sky was a completely unknown world. They could only imagine what existed above the clouds. Therefore, it is said that the legend of the raijū was born from the belief that unknown organisms lived in the sky and fell to earth during natural disasters like lightning strikes.
Raijū are given negative connotations as many things were happening in the sky beyond the reach of humans during the Edo period. 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.
It is believed that the myth of raijū originated from the Chinese materia medica text Bencao Gangmu.
Summarizing its physical characteristics simply, it is often said to be a mammal resembling a puppy or tanuki, about 2 shaku (approx. 60 cm) in length, with a tail of 7 to 8 sun (approx. 21 to 24 cm) and sharp claws. However, detailed forms and features differ by source:
- ' (Tenpō era book): States that raijū live on Mt. Tateshina (Nagano), also called "Thunder Peak". This raijū looks like a puppy with fur resembling a badger and five eagle-like sharp claws. It is also called "Thousand-year Mole" because it digs holes and enters the earth in winter. Experts have pointed out that drawings of raijū in Edo period books depict masked palm civets.
While masked palm civets are native to southern, eastern, and southeastern Asia, some scholars believe they were brought to Japan by soldiers during World War II as pets.
In Shinano Province during the Edo period, raijū were called "Thousand-year Weasels" and were displayed at Ryōgoku. These have been pointed out to be fakes crafted from weasels or badgers. Its origin and legend are unknown, but it has a cat-like appearance, is about 35 cm long, and is posed in a threatening stance with bared fangs.
Fuji Shrine (written with characters for "Wisteria") in Imayo-cho, Higashiōmi, Shiga, is a rare shrine that worships a raijū. Legend states that the village once suffered from frequent lightning strikes. A passing Yamabushi declared that a raijū living in the village was the cause. He had the locals build a large net and set it in the forest on the village outskirts. When black clouds formed and thunder began, a red-black beast appeared on the net. The yamabushi immediately caught it—it was a dog-like beast with a beak and sharp claws—and beat it to death with an iron staff. He declared his duty done and left. The lightning ceased, and a shrine was built in the forest where the beast was caught. This shrine was called "Fūjikome" (Sealing) Shrine to signify sealing the raijū, and the characters were later changed to "Fuji".