Book twenty (20.4293-4516) of the Man'yōshū comprises 224 poems (218 tanka, six chōka) with unspecified genres. From the social point of view this book is the most varied one, as it includes poems from empresses and princes, various strata of the nobility, down to the lowest border guard soldiers. Organized chronologically, book twenty is important for two important reasons. First, it contains many poems written in Eastern Old Japanese. Second, given the fact that many authors of the poems written in Western Old Japanese are well known historical and...