Raiju
Physical Description
Raiju in the Japanese language translates into thunder animal. And this is a most appropriate name for a creature that serves as a personal steed for Raidin, the Shinto God of Thunder. Composed entirely from lightning, this usually peaceable creature becomes agitated and high-strung during a violent lightning storm, transforming itself into a dervish of lightning that crashes into trees, fields and even buildings with normally disastrous consequences for the unfortunate object on the recieving end of the collision. In this present age, some are still wont to comment that a tree displaying the scorch marks of a lightning strike, is actually bearing the claw-marks of this beast. In its more composed moods, Raiju prefers to assume the shape of a cat, monkey, racoon, badger or weasel, but even in these more sedate states, it is still disposed towards inflicting some damage as it exercises its claws on the surfaces of some object. His cry was also believed to mimic the sound of thunder.
Story
Notorious for slumbering against the wishes of its master, Raiju sometimes exibits this curious habit of choosing to slumber in a person's navel, taking advantage of the individual's own tranquil state of sleep to do this un-noticed. Sadly, this often has tragic results for the sleeper selected to by Raiju to become its bed, when Raidin hurls an arrow of lightning into the belly of that ill-fated one, eager to goad his indolent creature into stirring awake. To avoid a painful demise of this nature, people would often sleep on their bellies during a raging storm when Raiju was most likely to be out and about. That way, they could ensure that the thunder beast would have no way of making them a prime target for Raidin's missiles of doom.
Orgin
The myth of the thunder animal probably came about as a way of explaining the natural phenomenen of ball lightning.