Several studies have classified Japanese dialects into multiple categories based on various attributes such as vocabulary, grammar, and phonology. Although analyses based on structural linguistics systematic criteria have been conducted, it would be worthwhile to perform a classification that incorporates the frequency of actual language usage in real-life activities. Hence, in this study, the frequency of mora bigrams occurring in natural discourse was employed for creating a phylogenetic tree by applying the neighbor joining method, and each dialect was thereby classified. Consequently, the dialects were classified as eastern and western, with the northern Alps being considered as the segregating border between east and west regions. Both Gifu and Aichi dialects were classified as western. Furthermore, in order to examine the characteristics of mora bigrams occurring in eastern and western dialects, comparison tests were conducted. Obtained results show that "Nda, NeR, Daka, Qte, DaQ, Dayo, Gara" in western dialects and " NaR, MoR, Rte, Hoi, N-ya, N-ja, Soya" in western dialects can be extracted as characteristic mora bigrams.
