Japan's economic rise was a major factor since it looked like Japan would become the new global economic powerhouse. This produced a keen interest in Japanese culture with a lot of concepts being popularised in this west, either from Japan itself or immigrant populations.

Secondly the ninja concept was introduced to the US via film as a way of revitalising the Kung Fu movie formula, which was copied by western film makers starting with Enter the Ninja in 1981 which was very influential. Ultimately these kind of movies were cheap to make while the stereotypical ninja suit obscured the actor so stunt doubles didn't need to be so exact. Because of American cultural power the idea of the ninja was spread around the world.

In addition Japanese culture got a lot more exposure in general with anime exportation and Japan's post 1983 place in the video game industry.