Interesting fixations we have, the Chinese have the unlucky number as 4, I think it's the same in Singapore. For them 13 is totally normal.
It's funny how it's the superstition that you grew up with that affects you, for example a rugaru won't affect you because you are not Japanese, but for a Japenese the same could be said with the classic demon.
You never seem to find a universal superstition that defies borders and cultures.
Oh, great post! It's certainly refreshing. :)