His name is derived from the Japanese words rai(雷, "thunder") and "god" or "kami" (神,shin). He is typically depicted as a demon-looking spirit beating drums to create thunder, usually with the symbol tomoe drawn on the drums. He is also known by the following names:
Yakusa no ikazuchi no kami: Yakusa (八, eight) and ikazuchi (雷, thunder) and kami (神, spirit or deity)
Kaminari-sama: kaminari (雷, kaminari, thunder) and -sama (様, a Japanese honorific meaning "master")
Raiden-sama: rai (雷, thunder), den (電, lightning), and -sama (様, master)
Narukami: naru (鳴, thundering/rolling) and kami (神, spirit or deity)
Raijin was created by the divine pair Izanami and Izanagi after the creation of Japan. There is a legend which says the eight lightning gods were charged with protection of the Dharma by the Buddha. This kind of syncretism is not unusual in Japan, even after the Buddha-kami separation order.
Some Japanese parents tell their children to hide their belly buttons (or navels) during thunderstorms. This is due to a folk belief that Raijin is sometimes credited with eating the navels or abdomens of children, and in the event of thunder, parents traditionally tell their children to hide their navels so that they are not taken away. Raijin's companion is the demon Raiju. In Japanese art, the deity is known to challenge Fūjin, the wind god.