Shintoism, or simply Shinto, is the ancient and historical religion of Japan. A pantheistic religion, Shintoism accords worship to gods or spirits that can reside locally at particular shrines, or globally, such as the sun goddess Amaterasu. Probably evolved out of a patchwork of rituals and gods from the original settlers in Japan, Shintoism has animistic aspects; that is, the belief that spirits reside in natural inanimate objects, in fact, in all things. It is of prime concern to Shintoism that one live in harmony with nature.
Shintoism is perhaps as much a philosophy and culture as a religion -- there exist no sacred texts, no defined prayers and no formal mandatory rituals. Instead, rituals are specific to particular shrines, families or gods. Often mischaracterized as 'ancestor worship', Shintoism respects the kami or spiritual entities that surround us. These can be gods, the spirit of a particular place or the spirits of one's ancestors.
Shintoism has coexisted with Buddhism literally for centuries, and many of the Japanese traditional gods have found their way into Buddhist pantheons. The karmic and cycle-of-life beliefs of Buddhism have integrated with the animism of Shintoism to form a particular whole that is unique to Japan. There is no requirement that a believer of Shinto forswear all other belief systems, and hence it peacefully co-exists with other religions that likewise have no exclusivity clause in their creed.
Shintoism was the official state religion of Japan prior to World War II, and the Emperor was decreed to be a living god descended directly from Amaterasu, the Sun Goddess. The word kamikaze comes from the words for 'divine wind', which the kami, or spiritual forces, were expected to send to keep Japan safe from foreign invaders. The failure of the kami to protect Japan from occupation led to some loss of status for Shintoism, and the Emperor, perhaps to restore it, declared himself unrelated to the goddess and not personally divine. Because of the unobtrusiveness of Shinto practices, however, and the very personal and familial nature of the various rituals that make up Shintoism, it continues to be practiced in many households in Japan, often side by side with Buddhism.