Just to nit-pick, the Japanese never really figured out how to produce composite bows, the Yumi was just laminated bamboo. It was one of the reasons they couldn’t successfully invade Korea until they were given western tech.
It’s kinda ironic nowadays, but prior to the meiji restoration Japan was considered a cultural and technological backwater.
The mountainous island with no metal? The one that shut itself off for three centuries? Technologically limited? Perish the thought.