[Nyororin]

A bit late to this discussion, but I'll toss in my info.

Japan has plenty of online relationship related culture, and plenty of sites to cater to it. In fact, I would even be willing to go out on a limb and say that Japan had "online" relationships before there even was an "online".
With the tradition of arranged marriages and a culture that hasn't historically catered so much to "love" as a main factor in a relationship - there have always been relationship services of some sort. From what I understand, there were services hundreds if years ago to introduce singles in distant villages to each other and the like. Dating services are a very traditional thing, really. Doing it online is really just a recent update.

You can find people wanting anything from a friend to a husband/wife online. It is still tradition for people to get special photos taken when they are 20 to use in the future for introduction services, on or offline.

The main markets though are people looking for no-commitment sex or to get married. The areas between are not very represented, so if you are looking for one or the other, great, but the pickings may be scarce if you are looking for normal dating.

When it comes to a relationship with someone outside of the country, things change a bit. There tends to be a pretty limited set of people... Mostly women who either can't manage a normal relationship in Japan (the type to run from!) or who want to be able to say they have a foreign boyfriend, but keep that at a distance so they don't really have to deal with any potential problems that might arise from a "real" relationship. And, of course, the freedom to just call it off whenever...

But, whatever floats your boat, I suppose. If you just want to be able to say you have a Japanese girlfriend, I am sure you won't have too much trouble finding a girl who just wants to be able to say that she has a foreign boyfriend.