Japanese has a number of sentence particles, which include both sentence-final particles (shuujoshi) and sentence-internal particles (kantoojoshi). Since sentence particles are not used as content words, they do not carry referential meaning. Typically they occur in face-to-face interaction and index various speech acts. Thus, they are essential in sense making in face-to-face interaction. To become a competent speaker of Japanese, then, it is crucial that young Japanese children acquire and use them appropriately. The social meaning of a sentence particle at least in part emerges from the immediate speech context, so it differs from context to context. For this reason, it is often beyond the limits of the native speakers' conscious awareness. Although there are many sentence particles, in this chapter I discuss three particles, ne, yo, and no, for they occur most frequently in adult conversation (National Language Institute reported in Yamada, 1980) and are the first sentence particles that emerge in children's speech (e.g. Clancy, 1985).
The particles ne and yo have been analyzed in terms of the degree of the speaker's joint access to or possession of information with the addressee (Kamio, 1991; Maynard, 1997). In this analysis, the particle ne is a marker of information shared between the speaker and the addressee, while the particle yo is a marker of information solely claimed by the speaker.