In recent years the hikikomori (social withdrawal) phenomenon described in Japan has also come to be seen in Europe, particularly France. Despite the high level of interest in hikikomori in France, it has not been clearly defined and there is no clear overall understanding of the phenomenon. Our Japanese-French research team, supported by a Grant-in-Aid for Scientific Research (B) (overseas surveys), compared hikikomori youths in France and Japan from the perspectives of researchers in various fields. The aim of this study was to investigate the kinds of people to whom the concept of hikikomori is applied in France and Japan. A clinical conference was held in Paris in September 2010 to discuss cases considered to be hikikomori in the two countries. This article is an interim report from research in the first year of a series of international joint studies, and describes the commonalities and differences in the state of hikikomori in Japan and France.