SBF:
If Japan is experiences secularisation in any way similar to that in western countries
Doesn't secularization require a prior state of non-secularization? How would Japan of the pre-1990s qualify? Haven't they been "secular" for a long time already? By attempting to compare it with westernized, i.e., European and N. American countries, aren't you comparing apples and moon rocks? Japan was never religious like those westernized countries which have gone secular from the effects of nominal Christianity. Sure the Japanese have had Shinto and Buddhism for a long time, but did those religions have any effect equal to the eastern Orthodox, RC, and early Protestant ones where many European governments were run by devoted religionists, had state churches, and so on? No way.
It's still apples and moon rocks.