Japanese/Korean Linguistics

The tonal correspondences between Japanese and Ryukyuan show a systematic split in which a single Middle Japanese tonal class corresponds to more than one Proto-Ryukyuan class. This pattern is crucial for reconstructing the Proto-Japonic tonal system, because it has generally been taken to imply tonal contrasts not preserved in Japanese. In contrast, the present account attributes the split to a conditioned rightward accent shift in pre-Proto-Ryukyuan. The shift merged Middle Japanese Classes 2.4–2.5 with Class 2.3 but was blocked by two factors: a word-final high vowel and the retention of an original word-internal morpheme boundary. Evidence for the latter comes from rare non-final e₁ and o₁ in Old Japanese, apparent violations of Arisaka’s Law, unexpected heavy initial syllables in modern Japanese varieties, and etymological reconstruction. The analysis accounts for most correspondences without reconstructing additional tonal classes in Proto-Japonic and highlights the role of morphological restructuring in tonal change.