Japan is about as safe from Islamic terrorism as you can get. Glad for you.
I lived in Japan for three years. They are safe because they racially profile. Not just middle eastern looking men, but everyone who is not Japanese. They have a very closed society and are extraordinarily suspicious of strangers. For 3 years, I shopped at a small local grocery near where my daughter took dance classes. It was only in the last 6 months I shopped there that the same girls at the register would say hello.. and I am a petite non threatening woman... but as an American I was suspicious.