So far, I have had fewer opportunities to work with Japanese collaborators than one would hope. There are several reasons for this. First, this is not a front door process per se so much as you get the word out and meet people and things happen behind the scenes. Second, much of the Japanese academic process is different. For instance, many PhDs -- even in the humanities -- are contingent on publishing. That's right -- if you don't publish 3 articles you don't get your PhD. There are further rules complicating when and how you can publish these concerning "national" and "regional" journals. But odds on as a foreigner, you have not heard of any of these.
Much of the faculty publishing also depends on a similar Japan-internal ranking system that seems like it was designed to copy impact factors. But then it was turned inward to make it so that national level publications in Japan are seen as equivalent to say Nature and Science for promotion purposes. Moreover, submitting to these journals and getting accepted is more an invitation-process than a peer-review process here. As a junior faculty member or graduate student, you get told when you can submit something. Often the inroad is a presentation. In fact, the Japanese faculty I have met by and large believe that this is the standard route of publication -- you present, you are asked to submit this for "peer review," and you turn that in.Thus, people are defensive about letting foreigners in -- because they see you as competition.
All of this serves as background for my experience. My experience so far is that faculty members are great and easy to work with. So are MA students. PhD students have been another story. I've made one presentation at a Japanese conference in Japanese. I was recently asked to be involved in an important translation project by a faculty member here. I asked him if he had a suggestion for a Japanese collaborator... So far so good.
Earlier last week I met with this collaborator. He has supreme confidence in his English ability -- unfortunately not matched by his ability. Our task is to translate an upcoming paper so that it can appear in a prestigious journal. I understand that I cannot produce such high quality work on my own, but he seems to imagine he could translate it to English that well on his own. I've seen his outline -- it's not that good. Meeting with him was probably the rudest experience I've undergone in Japan since I arrived. So as basic rule, avoid working with PhD students.