In Japanese Myth Raijin is one of the god's of Thunder. He is depicted as being a muscled man carrying a series of drums, which he uses to make the rumbling sound of thunder.
In some legends, it is written that he and Fujin were originally demons that opposed the gods. The great Buddha ordered his army to capture them. Then after a battle, consisting of the two demons and 33 gods, the demons were captured and converted.