Koniya Sign, or Amami Oshima Sign (AOSL), is a village sign language, or group of languages, on Amami Ōshima, the largest island in the Amami Islands of Japan. In the region of Koniya on the island, there exist a high incidence of congenital deafness, which is dominant and tends to run in a few families; moreover, the difficulty of the terrain has kept these families largely separated, so that there is extreme lexical geographical diversity across the island, and AOSL is therefore perhaps not a single language.