The problem in Japan now is the new crop of youth that are protesting day in and day out in support of religious freedoms specifically to be kinder and more accepting of Muslims. You are right about Japan today, but look how other countries have changed their immigration laws in the past decade and you will see what can happen to Japan when youth smoking crack protest endlessly.
If you need an example here is one, you can read lots of this nutty trend in Japan online. Remember, once upon a time China was Muslim free at least no Radical Terrorists, now parts of it have become infested real bad and it happened real quick, glad the Chinese exterminated a bunch of them last week.
Islam in China has existed through 1,400 years of continuous interaction with chinese society, according to wikipedia. They are 2% of the population. Like 25 million. That's too much imo, but I don't think they are a threat to chinese society, especially when they are executing them.
They estimate muslim population to be under 30 million by the year 2030
I do hope the japanese government won't give in to these protests, tho
