Tattoos, desire and violence
I found this book called "Tattoos, desire and violence", by Karin Elizabeth Beeler, which offers some interesting perspectives on "The Pillow Book". You have to look for the parts concerning the film, as it deals with many other themes, but those are also worth reading.
Here is an excerpt: (SPOILERS)
"After Jerome's death, Nagiko has the text of this book [The Book Of The Lover] tattooed onto her breast in blue-black and orange-red, with a design that incorporates the last calligraphic writing on Jerome's body, thus symbolizing a re-union with Jerome and the restoration of her own text. This tattoo is somewhat reminiscent of the practices of Japanese courtesans who tattooed "kisho bori" (promise engravings) on hidden parts of their bodies, visible only when naked or in the act of love."
In case anyone is interested, here is the link for the complete book: