1. Post the entirety of the article here, forum disallows threads with just links. If you cannot replicate the article at least give a brief summary of whats in it.
2. The article gives no statistic. It does delve into the reasons for the growing Japanese Muslim population but then what is the increase rate? What statistic or data leads you or the article to believe its the fastest growing religion over there.
Annual growth rate vs other religions?
Domestic muslim population vs immigrant population?
The number of mosques built in the last two decades?
Availability of the holy Quran in Japanese bookstores, is it available ? How many stores offer it?