zuihitsu

a genre of Japanese literature consisting of loosely connected personal essays and fragmented ideas that typically respond to the author’s surroundings. The name is derived from two Kanjis meaning “to follow” and “brush”, and thus works of the genre should be considered not as traditionally planned literary pieces but rather as casual or random jottings down of thought by their authors. (wikipedia, zuihitsu)

Example: Hōjōki, An Account of My Hut

Also, The Pillow Book, Sei Shonagon, Makura no soshi

Study: Formless in Form: Kenko, Tsurezuregusa and the Rhetoric of Japanese Fragmentary Prose, by Linda Chance