This paper assesses the definitions of the terms “deaf” and “Japanese sign language” based on the structure of the language and culture specific to deaf persons. The classification of widely used signs is reexamined from a sociolinguistic perspective. The discussion in this paper suggests the following: (1) The definitions inevitably vary because sign language groups are created and grow under the influence of “hearing impairment.” (2) The term “Japanese sign language” was proposed as a rhetorical counterpart to manually coded Japanese rather than “Japanese (spoken) language.” This positions the right pole of the linguistic continuum as manually coded Japanese. (3) The “There are two sign languages” and “There is only one sign language” arguments are based on political backgrounds. Based on these results, we propose that explaining the language use of signs from a sociolinguistic perspective entails the exclusion of artificial languages and sign language learners who can hear from the scope of the study. Furthermore, the classification of signs should be assessed among speakers with hearing impairment whose primary means of communication is sign language.

In this paper, I focus of Signed Japanese (SJ) and its signers that are externalized as a "not sign language" or "not Deaf people," based on the field data which I gathered from participant observation. SJ is "not sign language" in sign language linguistics, and as a result, SJ signers have been placed in a suspended state of "being nothing." However, SJ signers have been weaving a peaceful life as Deaf people who are "not Deaf, but rather Deaf people," strategically foreclose some Japanese Sign Language (JSL) signers and good sense who consider only JSL signers as "right" Deaf people. Against this background, I propose that there be often a divergence between the academic definition of the concept of "Deaf" and the widely shared definition of "Deaf" in the Deaf community, and I argue that it is not possible to show the superiority of one definition over the other.

Movement is a phonological parameter of sign language, and it is considered difficult for learners to acquire. Moreover, the acquisition of prosody is essential for natural signing. In this study, I focused on the movement and prosody of sign language to investigate what errors can be seen when hearing persons learn sign language, which involves visual-gestural modality. Five hearing subjects were shown a silent movie and asked to sign its content. Deaf subjects then pointed out areas they found unnatural and these areas were analyzed. As a result, the following errors were observed: ① Rhythmic breakdown due to excessive use of mouthing, ② Lack of sign lowering and excessive repetition, ③ Repetitive pointing and contact with the non-dominant hand, ④ Loss of non-manual markers, and ⑤ Co-occurring errors of prosodic and non-manual markers, suggesting that the hearing subjects had a peculiar “accent” in regards to their movement and prosody.

This paper is intended to discuss how the sign language are used and spread in Japan from the perspective of Deaf researcher whose native language is Nippon Shuwa Gengo. Nippon Shuwa Gengo as a descriptive grammar of the natural sign language of Japan is routinely transformed by social, historical, and political backgrounds, while being influenced by the Japanese language. In fact, there are many Deaf people and sign language learners who cannot understand the difference between so-called Japanese Sign Language and Signing Exact Japanese, or Signed Japanese, as some sign language teachers and sign language researchers claim. The main reason for it is that many people mistakenly believe that the meaning of the Japanese gloss attached to each sign language expression is exactly the same as the meaning of the sign language expression itself. Furthermore, although there is a sign (visual) language that has been passed down from generation to generation on the platform of the sign language grammar (regularities, word order, and expressions, etc.) that was naturally generated, developed, and matured by the instincts of our Deaf ancestors, sign language expressions that ignore this sign language grammar are increasingly being created and spread more and more. This is the reason why Nippon Shuwa Gengo has changed so much. The influence of Japanese gloss is so great that Nippon Shuwa Gengo has been transformed. This paper clarifies the reality of the use of Nippon Shuwa Gengo.

We can observe simultaneous/successive occurrence of fingerspelling letters as manual signs or mouthings as nonmanual signs with sign constructions in linguistic/semiotic expression by d/Deaf or hearing signers. In this paper, we focused the mouthings co-occurred with sign constructions, and considered the linguistic/semiotic characters of mouthings by using the hyperextended semiotic schema. In addition, we analysed the dynamic behaviour of components in co-occurrence of mouthings and sign constructions by using the theory of ruby, the triangular semiotic model, the translanguaging theory, and the usage-based grammars, contributing to the sign language studies including the linguistics and semiotics.