More studies outside of Japan have been conducted. If you have the patience to wait for either of these sites to download you can read about the study of it by Danish students, or watch this documentary. It appears too that soon it won't be just a "Japan thing". Already the term is spreading in a pop-phrase way on the web at least, here on a site about kinematics, being used in blog names, and several usernames. In fact we even have our own. And while the 2004 film Hikikomori: Tokyo Plastic seems to have a ludicrous plot - cases of violence by Hikikomori are real.
引き篭り (hikikomori) is often described as a recent phenomenon which is seen mainly in Japan - but how does it compare to the time-honoured tradition of hermits? Is it unnatural to pursue solitude?