Edo, December 1693. Lord Mitsuyoshi, the shogun’s heir, is found stabbed through the eye in a Yoshiwara house of assignation. The courtesan Lady Wisteria, who spent the night with him and once had a relationship with Sano, has vanished together with the private journal that may explain the crime.
Sano, Reiko and Hirata investigate within the regulated pleasure quarter while their political enemies exploit Sano’s connection to the missing woman. The pillow book records secrets capable of changing the succession, but finding it requires separating Wisteria’s carefully constructed public identity from the alliances and injuries hidden in her past.