About the language: every island in the Okinawan chain has its own language (ex: Yonaguni-go) and there are several "dialects" on the mainland that are unintelligible to speakers of standard Japanese (ex: Fukui-ben and Tsugaru-ben).
If you define a language as mutually intelligible speech, there are easily over a dozen languages in Japan. Many of them are unfortunately dying, though.
About the language: every island in the Okinawan chain has its own language (ex: Yonaguni-go) and there are several "dialects" on the mainland that are unintelligible to speakers of standard Japanese (ex: Fukui-ben and Tsugaru-ben).
If you define a language as mutually intelligible speech, there are easily over a dozen languages in Japan. Many of them are unfortunately dying, though.
You're absolutely right, Ryukyuan is a entire subfamily within Japonic. Thanks for pointing that it.