While it is uncontroversial that a primary rhetorical tool in Japanese poetry such as Tanka and Haiku is mora count, rap artists in Japanese hip hop music have been incorporating the western notion of rhyming in this increasingly popular music genre. In this paper we shall demonstrate that the rhyming patterns observed in Japanese rap lyrics provide another piece of evidence for the importance of mora in Japanese. However, we will show that the three realizations of mora, i.e., vowel, moraic nasal, and geminate, do not play an equal role in rhyming.
An examination of three Japanese rap musicians' lyrics reveals that the most frequent rhyming pattern involve rhymes with two identical vowels (including a long vowel). Moraic nasals rhyme with one another, but an equally frequent pattern is for a moraic nasal to rhyme with a vowel. While we find geminate-geminate rhyming, the patterns in which a geminate rhymes with a vowel or a geminate rhymes with a moraic nasal are not instantiated in our samples. This asymmetrical situation among the three instances of mora is interesting given that all these three manifestations of mora have generally been treated equal. Although the notion of mora and their three instantiations still constitute an important notion in accounting for the rhyming patterns in Japanese hip hop, it is also intriguing to observe that the three instances may not have the same level of recognition as a rhyming unit.
The concept of mora has long been identified as one of the most difficult for learners to acquire, but its effective pedagogical treatments are rare. Focusing on frequently occurring rhyming patterns, we will demonstrate a few exercises based on rap rhyming that are intended to improve learners' acquisition.