I see a lot of "what is the Japanese attitude to XYZ" posts and just want to make sure everyone knows that although there may be some kind of average view on something it is not that clear cut.
Like anywhere in the world, people differ and will all have a different view to, and knowledge of, any given topic.
Not got a serious answer to the question on the average view, but you better hope it is not related to how the Swedish girl was portrayed in the TV Drama 日本人が日本語知らなし
iirc the Swedish girl thinks ninjas are real, and that she can meet one and become one and be their friend
and goes into the woods to meet one and almost gets kidnapped for being so naiive.