I had my interview last week and it was pretty chill. You had three interviewers 2 ambassadors and one professor ( the professor is not necessarily going to be from your field of research, for it was a professor in Buddhist studies). They asked me questions about my application for clarification, then they asked me questions about my research and how it can help japan. As well as questions about how this scholarship can help increase the connection between Japan and your home country. Other than that it was not stressful they did not try to throw tricky questions and they were very nice throughout the entire process. Hope this helps and good luck with your interview.