Okay so now I’m on a Shaman King kick and I got more stuff I wanna gush about that I just think is super rad. As a young weebling one of the things that really struck me about Shaman King was how it was a rare case of Japanese faiths and mysticisms being made fairly distinct from one another in a relevant way, as much of Japanese media either picks one to focus on, or kind of melds two or more together with the implicit assumption that of course a Japanese primary audience will understand the implications of the various different terms and iconography. This is a cultural gap not generally accounted for in exporting and translating these kinds of stories for a secondary non-Japanese audience.
So, a little primer: Japan’s national religion is Shinto, which is in fact a long standing religion of the Japanese islands dating back to the 8th century. It is also one of the few surviving animist & shamanist religions in the world: Shamanism describes any religion in which a distinct ritual of spiritual communion is central to the practice and faith, and Animism refers to the belief that all things in the world possess their own innate spirit or essence. (as opposed to just people.) The Shinto faith is where the iconic red Tori gates come from, where the massive wound ropes belted around massive ancient trees, and zigzag Shido paper wards come from. As well as the iconic, if a little awkwardly fetishized Miko shrine maid attire is from as well.
Anna is an Itako, an eclectic form of spirit medium within the Shinto faith. Notably, the practice is in steep decline, with all of its very few remaining Itako being over the age of 40.
(As a small aside here, a minor character toward the end of the manga also practices Ushi-no-toki-mairi, which is a kind of ritual curse rooted in Shinto, but not itself core to the faith.)
However, Shinto is not the only religion prominent in or native to Japan! Second to and indeed hand in hand with Shinto is Buddhism, taken from China, which of course took it from India. Japanese Buddhism underwent various revisions and adaptations to find its home in the Japanese culture, as well as its own uniquely Japanese iterations like the now iconic Zen Buddhism which was once the subject of one (of many) waves of Japanophilia that pulled Western interests. However it's of a little less interest in Shaman King...
But Buddhism isn’t the only faith that Japan adopted from China. Chinese Daoism came to Japan in the form of Onmyodo. Less of a religion, Onmyo practices at the hands of Onmyoji involved various forms of geomancy, meteorology, divination and theories of the flow of energies according to the balance of yin and yang. In fact the name Onmyodo effectively translates as “The Way of Yin and Yang.”
It’s from the influence of Onmyodo that the Japanese came about the concept of the bodily energy known as Ki/Chi. At the height of their cultural influence, Onmyoji actually occupied a very powerful position in Japanese aristocracy as advisors to figures of power, and in turn many wielded almost as much if not more power and respect as the minds behind those ruling figures.
Of these mystic and proto-scientific advisors Abe-no-Seimei has endured as perhaps the most famous name among them, although largely in myth. Exaggerations of his power of prophecy and wonderworking grew so out of control that some mytho-historical accounts have tried to attribute his knowledge to magical powers inherited from alternatively either half Oni or fox-spirit parentage. His name is often dropped with little explanation in anime and manga and video games, but more often the distinct image of the onmyoji based on his character are also widespread even without mention of him in particular. The clean white robes, and tall courtly hat are most recognizable.
In Shaman King, the Asakura family that the hero Yoh and his twin brother (and series villain) Hao are born into are a family of Onmyo mystics. Yoh's engagement to Anna the Itako is a kind of political marriage to merge two powerful lineages if shamans. Bringing together two of Japan's biggest faiths. But that's not all!
Shugendo is another indigenous religion of Japan that is arguably even older than Shinto. It’s a little less seen in pop culture these days but it’s most notably represented by Tengu, the somewhat erroneously translated “goblins” of the Japanese mountains. The Tengu have two general depictions, as either a long nosed and red faced monster of a man, or a humanoid crow, both winged and adorned in traditional Shugenja attire. The small geometric hat worn forward on the head, short coat with tassels or pommels down the chest, and the ringed staff are all distinct aspects of the a traditional shugenja. In addition, pop culture depictions often reflect the faith’s worship of the mountains and forest through wild unkempt hair and beards, and the disciplinary practice of sitting beneath a cold and crashing waterfall for meditation.
Yoh's father Miki is a shugenja, a rough around the edges aescetic without a strict background and without a dynasty of shamans behind him, reflecting the kind of obscure and neglected faith of shugendo in modern Japan. Having married into the Asakura family, he lends the twins a third powerful Japanese faith, making them both a kind of perfect merging point of Japanese religions and mysticisms!
And finally, Shaman King also makes heavy reference to the Ainu peoples indigenous to Japan's northern island of Hokkaido, but not directly thru Yoh as a character. Instead they are represented in the rival and supporting hero, Horohoro. There is however A LOT to the history of the Ainu and their faith and relation with the rest of Japan and the genocide commited against them by the central Japanese. I'm not about to get into all of that here and now. It is its own monster of a post, and honestly i dont know that i even feel qualified to summarize it, let alot get into the nitty gritty. But i super encourage anyone to look up the history of the Ainu themselves and learn what you can!