[T]he earliest traces of cannabis in Japan are seeds and woven fibers discovered in the west of the country dating back to the Jomon Period (10,000 BC – 300 BC). Archaeologists suggest that cannabis fibers were used for clothes – as well as for bow strings and fishing lines. These plants were likely cannabis sativa – prized for its strong fibers – a thesis supported by a Japanese prehistoric cave painting which appears to show a tall spindly plant with cannabis’s tell-tale leaves.
Until World War II, it was an important commercial crop in Japan.
This changed after World War II, and Japan now has some of the most strict anti-cannabis laws in the world.