Setsuwa are based foremost on oral tradition and existed primarily as folktales or in other non-written forms before being recorded and committed to text.
Although there are no formal rules regarding what constitutes setsuwa as a genre, stories in the setsuwa style "have in common brevity; an uncomplicated plot unfolded in plain, direct language; character delineation through dialogue and action rather than through description and psychological analysis; and a predilection for amusing, startling, dramatic, or marvelous subject matter.
Nihon Ryōiki was compiled in the early 9th century (Heian period) by the monk Kyōkai, and contains 116 stories split between three volumes as well as nine poems.
These stories originate both from older sources and from times contemporary to the compilation’s completion, and— like many Buddhist setsuwa— are often focused on the concept of karmic retribution.
Konjaku Monogatarishū contains over one thousand tales, and the works draw their content largely from folklore— both Buddhist and secular— from India, China, and Japan.