Japan has for centuries been a closed community. They have shunned both immigration and emigration under what they call “sakoku”. It is a ‘Japan for Japanese’ policy that is centuries old and is the reason that there are few minority groups with a population anywhere close to 1%. In fact, all of the minority groups together make up less than 1.5% of their population.
It is easy to criticise this isolationism in a modern world where national boundaries are increasingly being eroded especially if you are a left-wing, global village adherent. However, Japan has the advantage of being, perhaps the only sizable population that has not experienced any terrorism, including Islamic based attacks.