First, Yonaguni. Then, Amami Oshima and Miyakojima. Next is Ishigaki.
Each of those southern islands have seen or will see expansion of Ground Self-Defense Force units and facilities. This expansion of the Self-Defense Forces' presence across the "first island chain" is part of Japan's "southwest island defense" design. The personnel there are positioning against a potential Senkaku Islands crisis and increasing transit of Chinese military aircraft and vessels through the area.
For Japan, self-reliance is particularly important with these bases because of the "gray zone" threat they represent. Of course, as with most things defense-related in Japan, domestic politics plays a notable role in the process, and negotiating acceptance of the new facilities without imposing too many operational constraints will be a challenging balancing act for the government.