Iwakura
Along the Kaido, some megaliths have carvings related to Buddhism, while others have legends associated with them, such as the tale of a famous samurai who bridged horses. The Iwakura Gakkai research group believes that the worship of rock formations and megaliths can be traced back to the Jomon period. They argue that some rock formations were artificially arranged to represent certain figures, directions, or even the shape of a constellation. However, the Iwakura Society disputes this view, stating that the Iwakura ritual did not begin until the Kofun period. Additionally, there is criticism of the idea that megaliths are human-made artifacts.