In order to determine some of the necessary social skills for cross-cultural adjustment of International students in Japan, their overt behavioral difficulties were analyzed. In the first survey, 24 students described (1) some of the Japanese behavior which were difficult for them to understand and follow, and (2) some of their own behavior which were misunderstood or not easily accepted by Japanese. Responses were summarized through the KJ method into the following six categories: indirect expression; social manners; suppressed expression; relationship with different genders; attitude toward foreigners; and group-oriented behavior. In the second survey, 202 students were asked to list up to three socially difficult situations and 102 valid responses were analyzed. Results showed that the following groups of subjects experienced particular difficulty in aspects that follow: 1. female: social manners, 2. Europeans and Latin Americans: suppressed expression, 3. South-east Asians: attitude toward foreigners. In comparison, the following groups were well off with respect to the following aspects: 1. South-east Asians: indirect expressions, and 2. those who have been in Japan a substantial time: group-oriented behavior. A training model for Japanese social skills was proposed.