The Pillow Book of Lady Wisteria

In The Pillow Book of Lady Wisteria, Laura Joh Rowland once again has written a book in which "an exotic setting, seventeenth-century Japan, and a splendid mystery...make for grand entertainment" (New York Daily News).
In the carefully ordered world of seventeenth-century Japan, the Yoshiwara pleasure quarter is a place where men of all classes can drink, revel, and enjoy the favors of beautiful courtesans. But on a cold winter's dawn, Sano Ichiro—the shogun's Most Honorable Investigator of Events, Situations, and People—must visit Yoshiwara on a most unpleasant mission.
Within a house of assignation reserved for the wealthiest, most prominent men, a terrible murder has occurred. In a room that reeks of liquor and sex, the shogun's cousin and heir, Lord Mitsuyoshi, lies dead, a flowered hairpin embedded in his eye, in the bed of the famous courtesan, Lady Wisteria.
The shogun demands quick justice, but Sano's path is blocked by many obstacles, including the disappearance of Wisteria and her pillow book, a diary that may contain clues. The politics of court life, the whims of the shogun, and interference by his long time rival, Edo's Chief Police Commissioner Hoshina, also hinder Sano in his search for the killer. Sano's wife, Lady Reiko, is eager to help him, but he fears what she may uncover. When suspicion of murder falls upon Sano himself, he must find the real murderer to solve the case and clear his name.