The Ethnologue lists 15 languages in Japan. Ainu (ain) is spoken in the north by an estimated 15 people, Japanese is the national language, and Korean is spoken by an estimated 670,000 people (1988). Japanese Sign Language (jsl) is also spoken by about 315,000 people.
The other 11 languages are in the Ryukyuan family, located in Okinawa, a 1,000-kilometer-long archipelago of hundreds of islands extending from southern Kyushu to Taiwan.
The Ryukyuan languages are related to Japanese, but the connection is distant. Nevertheless, for social reasons, Japanese people (including Okinawans themselves) often refer to Ryukyuan languages as mere dialects of Japanese.
Enter Byron Fija, a half-Okinawan, half-American. Proud of his ability to speak Okinawan (ryu), also known as Central Okinawan or Uchinaaguchi, he teaches the language in an effort to maintain and revitalize it.
Read more in “Okinawans push to preserve unique language.” Also, “Okinawans Try to Preserve Dying Language” has part of that article with English subtitles/subtitles (after the opener), plus a video and more links.
The other languages listed in the Ethnologue with estimated populations are:
- Kikai (kzg) – 13,100
- Kunigami (xug) – 5,000
- Miyako (mvi) – 67,600
- Northern Amami-Oshima (ryn) – 10,000
- Oki-No-Erabu (okn) – 3,200
- Southern Amami-Oshima (ams) – 1,800
- Toku-No-Shima (tkn) – 5,100
- Yaeyama (rys) – 47,600
- Yonaguni (yoi) – 800
- Yoron (yox) – 950
Wikipedia does not have articles on all of these languages. See the article Amami language for languages without a link.