I think the divine sidekick would have to be Ryujin. The dragon god.

On the islands of Japan, having the company of the one who represents the phenomenal power of the oceans and can control the tides could be useful--and throw in his handy-dandy ability to take on human shape and blend in with “normal” society. He flies, and whether you could get away with riding on his back…

Also, a coral palace under the sea would make a great “Batcave” to both hide out in, or just chill. With a lot better view then simple cave walls…

Plus, he’s a freaking dragon. If you’re going to be Batman and Robin together, turning up with a rather large dragon in the role of Robin really lets you get away with saying “I’m the goddamned Batman!” (or the general equivalent at least). ;)

--Edward Higgins