Which oldest extant waka anthology is noted as having no preface?

Which oldest extant waka anthology is noted as having no preface? The Man'yōshū is the canonical answer.

The Man'yōshū is the oldest surviving anthology of Japanese-language poetry, compiled in the eighth century during the Nara period. Unlike later imperial waka collections, it does not begin with a formal literary preface explaining the nature of poetry, the purpose of the compilation, or its organizing principles.

That absence is especially noticeable when the Man'yōshū is compared with the Kokin Wakashū, completed around 905. The Kokin Wakashū famously has both a Japanese preface by Ki no Tsurayuki and a Classical Chinese preface by Ki no Yoshimochi. Those essays helped establish a learned critical framework for later court anthologies.

The Man'yōshū does contain short notes, headnotes, prose explanations, and inscriptions attached to individual poems. Those local annotations are not the same thing as an anthology-wide preface. This distinction explains why the collection is described as having no preface even though some poems are accompanied by substantial contextual prose.