Kojiki
Before traveling to Japan, I realized I knew very little of the foundation behind the Shinto religion. I thought, is there a ‘bible’ of sorts to help me understand? That search took me down the path of learning about the Kojiki.
First, the Kojiki is more like a compilation of ancient myths about creation, genealogies, and some early history of the islands of Japan to eventually lead back to the imperial line and provide it some legitimacy.
It starts with the myth of how the islands of Japan were created from the body of the deities Izanagi and Izanami, and Amaterasu. There are stories about Yomi, or underworld, where it’s established in the myth and related to Izanagi and Izanami as well.
There’s stories that start in myth but then manifest in the real world, such as the discovery of the Kusanagi sword. A recurring god, Susanoo the storm god, kills a multi headed serpent, and out of the monster’s tail discovers the sword. The sword is one of the three sacred treasures of the emperor, tying him directly back to a God.
There’s the story of the Japanese equivalent of Hercules, Yamato Takeru. He wields the kusanagi and conquered many foes.
However, there’s a long section of the book that is really about the genealogy, and this part of the book is quite lengthy and boring. Not really a narrative, more like a historical record likely to provide some textual basis of facts to establish the legitimacy of the emperor.
I think I’d recommend reading this only if you’re deeply deeply interested in Japanese folklore. Perhaps there is a more approachable version out there that is more readable.