Halloween isn't a huge deal in Japan, but it's big enough. Most department stores have children's costumes and a few have adult ones too (Halloween costumes that is, they always have nurses and school girls and things like that.) But there are a few things that are rather difficult to find. Costume makeup for one. It's easier to go and get the stuff from Cosmates, the same for wigs. I have not been able to find good vampire fangs though >.< I've been able to find the huge ones that look horrible, but not the smaller ones that stick on your teeth. I'm almost too the point of trying to make them, as I have found a good tutorial and the modeling stuff is actually really easy to find here.