Until now, discussions regarding universities with full-time English-taught programs (ETPs) have revolved around either domestic Japanese students or international students. Furthermore, improving the English skills of domestic Japanese students has been proposed as the main way of training human resources capable of achieving international success. However, an analysis of results from a readiness study and initial Japanese placement tests taken upon entry conducted among students in X University’s English-taught program revealed that there were students who have been educated in languages other than Japanese for extended periods of time while living abroad, despite Japanese being their native/heritage language or possessing Japanese citizenship. The results also showed that, after graduation, many students aspired to use Japan as a base to achieve international success. Thus, in discussing how to train students in English-taught programs to reach the capability of working internationally, it is necessary to (1) keep in mind that recognizing the diversity of students is more vital than maintaining the binary distinction of “domestic Japanese student” or “foreign international student”, and (2) consider differing qualities and available methods based on the fact that students carry diverse backgrounds.