Multiculturalism is always a lie. It just means that you have to give up your traditions to accommodate the demands of aliens.
Visiting a Shinto shrine isn't mandatory, it's just a nice thing for the kids to do. But for the Muslim kids it's apparently Haram. Since the Muslims are religiously prohibited, and the Japanese aren't religiously required, it's easier to just cancel it entirely.
Dietary prohibitions work the same way. The Muslim kids can't eat pork, so the school cafeteria stops serving pork. The Muslim kids have to eat halal, so everyone has to eat halal. That annoying vegan friend can't eat pepperoni, so everyone at the office has to settle for vegetarian pizza.
In any mixed environment, whoever has the most restrictive practices and the most intolerant beliefs will end up setting the standards that everyone else has to live by.
-Japanese Kindergarten visits Shinto Shrines every year
-Muslim Children from the Third World enroll
-Visits to Shinto Shrines cancelled because it's offensive to Muslims