This is an 11th century sort of Memoir. Both the author's name and the title of the book are liberties by the translator. We do not know the name of the woman who wrote the book and the book is called the Sarashina Nikki. Nikki is translated diary or journal, but neither is quite right and autobiographical reflections would probably be more accurate. It is most similar to the 19th century work 6 Records of a Floating Life.
While the title is from another work, the book both often recounts the dreams of the author and also has a dreamy quality. We are told about her dreams, her reading and her travels, but the ins and outs of her marriage being a parent and similar things are often skipped over. The book is absolutely a literary work and one of great beauty. It seems to be the cases that the female authors of the Heian period (who are the important authors) all infused their work with poetry. While much of the poetry is on stock topics it is all very beautiful. It is a short work and a dreamy introduction to a world that seems at times not only far away in time and space, but in another universe.