Did you know that in Pokémon, Raichu is based on a legendary creature in Japanese folklore called "Raijū", or the thunder beast who had the powers of lightning? Raikou, a legendary pokémon, is also based on this legend.
Raijū is said to be the companion of Raijin, the Shinto god of lightning. It is usually calm and harmless and likes to sleep on sleeping people's tummies! >3< In thunderstorms though, it becomes extremely playful and restless, jumping from tree to tree in meadows and forests. Lightning marks on trees are said to be caused by Raiju's claws.
(From Wikipedia)
Raijū (雷獣,"thunder animal" or "thunder beast") is a legendary creature from Japanese mythology. Its body is composed of lightning and may be in the shape of a cat, fox, weasel, or wolf. The form of a white and blue wolf (or even a wolf wrapped in lightning) is also common. It may also fly about as a ball of lightning (in fact, the creature may be an attempt to explain the phenomenon of lightning). Its cry sounds like thunder.
Another of Raiju's peculiar behaviors is sleeping in human navels. This prompts Raiden to shoot lightning arrows at Raiju 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 Raiju will only hide in the navels of people who sleep outdoors.
