There's an interesting featurette on "what's the deal with nuns in Japanese pop culture?" over on Kotaku.com.
It's got a couple of nuggets of interesting historical stuff, so it's a decent lightweight read. It is, however, a ridiculously shallow view (but hey -- it's Kotaku), and candy-coats at least one medium's portrayal of Judeo Christianity.
If you (for example) look at how Christianity is portrayed in Japanese animation (popularly, "anime"), like MD Geist and Evangelion (the latter of which mixes in Gnosticism and Kabbalism as the same thing), Macross, etc.) -- the religion is not popular. As a matter of fact, Christianity is often held up as the device from the West that literally brings about the end of the world.
That doesn't quite mesh with the Kotaku feature, which puts kind of a positive spin on Christianity's reception in Japan.
But none of that matters.
What does matter is the feature's reminder to me of the term, "Nunsploitation" -- Exploitation films about nuns, popularized in Europe in the 1970s (while the West was doing backsploitation). And then Japan was off and running with nunsploitation through the 80s and 90s.
Fascinating cultural stuff.