no one really knows the origin of the practice of constructing torii gates but can trace them back to a mention in a text from 922; the oldest wooden one was built in 1535

one theory is that they were originally bird perches, but that since birds are considered a symbol of death the “bird” word isn’t written onto them and the connection was lost with time. korean religions still have bird perch totems in their culture, which lend credence to this idea.

torii are seen as portals where kami (spirit archetypes/deities) arrive; the kami “counter” word is the same word as pole

when i look at pictures of torii with the double lintels on top its not hard to see a bird perch with a little roof on top