Yonaguni Ryukyuan, Dunan munui in the vernacular, is spoken on Yonaguni Island (Dunan ccima), which belongs to the Yaeyama district of the Okinawa prefecture, Japan. The island is the westernmost one in Japan and is located halfway between Taiwan and Iriomote Island. The Dunan language belongs to the Macro-Yaeyama subgroup of Southern Ryukyuan, and it is thus a sister language of Yaeyama Ryukyuan. All Dunan speakers are in their mid-fifties or older, and all of them are bilingual in both Standard Japanese and Dunan, while younger generations are usually monolingual in Japanese. The total number of Dunan speakers can be roughly estimated to be around 400.