The headnote explains that through this genre, "stories of the floating world," Saikaku is able to provide his contemporary audience a retelling of well-known events, in this case the execution of an almanac maker's wife, Osan, and Moemon, a trusted assistant of Osan's father. The headnote makes clear that this kind of storytelling, dealing with well-known events and told in a colloquial voice, was popular in part because it was accessible to an audience: it's easier for people to be interested, invested, and engaged in reading something that is relevant to them. This genre's success points to the importance of relevance. Western audiences even today should be able to understand this story's central conflict: a tension between individual desires and social roles and expectations. Still, this fiction is useful because it presents a stark contrast to what was going on in Europe at the time. Europeans at this time were bent on science and reason, often looking outward; in the East, the focus was often on reflection and internal investigation - here that idea takes shape as an investigation of the role of the individual as part of a larger social picture.
For more information about the Tokugawa period, see http://www.openhistory.org/jhdp/intro/node20.html.