Numerals and Timelines of a Shared Sign Language in Japan: Miyakubo Sign Language on Ehime-Oshima Island

The current study continues our effort to document a shared sign language in Japan—Miyakubo Sign Language (Miyakubo SL) on Ehime-Oshima Island, located in the western part of Japan. After a brief sociological, geographical, and cultural introduction to Miyakubo SL, the topics of numeral expressions and timelines in Miyakubo SL are discussed. A comparison of the numerical system to that of Japanese Sign Language clearly shows that the differences between Miyakubo SL and JSL extend beyond mere lexical variety. In addition, Miyakubo SL provides a new set of data for two types of timelines: a partial timeline that uses the signer's body as the point of reference, and a celestial timeline which refers to the movement of the sun.