You may not think so but Halloween is very popular in Japan. There are many events and festivals and people go around the streets dressed-up. They don't do the traditional 'trick or treat' but they simply have fun and walk on the streets in groups.
You don't believe me? See it yourself.
Next, I'm gonna post some japanese halloween costumes, maybe it can help you get some ideas. Click on the pics to enlarge.
A japanese Jack Sparrow, lol.
Classical japanese obake (ghost):
Love this one!
So cute!!
This one is a genius!
LOOOL male pink bunny!