This photo was taken in Japan. One of the billboards is in Japanese. In which language could the other one be?

The six Ryukyuan languages are the indigenous languages of the Ryukyu Islands, the southernmost part of the Japanese archipelago (including Okinawa). They are not mutually intelligible with Japanese or even with each other. Today, these languages are becoming endangered, and a new mixed language, based on Japanese and Okinawan, has developed, known as "Okinawan Japanese".