The film's title, "The Pillow Book", refers to an ancient Japanese diary, the book of observations by Sei Shōnagon (清少納言), actual name believed to be Kiyohara Nagiko (清原 諾子), from whence the protagonist's name in the film.
The film is narrated by Nagiko (Vivian Wu), a Japanese born model living in Hong Kong. Nagiko seeks a lover who can match her desire for carnal pleasure with her admiration for poetry and calligraphy. The roots of this obsession lie in her youth in Kyoto, when her father (Ken Ogata) would write characters of good fortune on her face. Nagiko's father celebrates her birthday retelling the Japanese creation myth and writing on her flesh in beautiful calligraphy, while her aunt (Hideko Yoshida) reads a list of "beautiful things" from Sei Shōnagon's the book of observations. Nagiko's aunt tells her that when she is twenty-eight years old, the official book of observations will be officially 1000 years old, and that she, Nagiko, will be the same age as Sei Shōnagon when she had written the book (in addition to sharing her first name). Nagiko also learns around this time that her father is in thrall to his publisher, "Yaji-san" (Yoshi Oida), who demands sexual favours from her father in exchange for publishing his work.
The publisher arranges Nagiko's wedding to his young apprentice. Her husband (Ken Mitsuishi), an expert archer, resents Nagiko's love for books and her desire to read, in spite of his apprenticeship. He also refuses to indulge in her desires for pleasure, refusing to write on her body. When he discovers and reads Nagiko's pillow book, he is extremely resentful, setting it on fire and thus setting fire to their marital home, an event which Nagiko describes to be the 'first major fire of [her] life.' Insulted and enraged, Nagiko leaves him for good.
Hiding from her husband, Nagiko moves to Hong Kong. In spite of her aversion to the practice, she learns how to type to find work. Outside her apartment, a group of activists regularly protest the publishing industry for the depletion of forests due to the need to make paper.
After working as a secretary in the office of a Japanese fashion designer for a while, Nagiko's employer takes a liking to her and makes her one of his models. As a successful fashion model, Nagiko hires a maid (Hideko Yoshida again), as she now finally has the opportunity to explore her sexual desires of being written on. However, after several affairs, she feels dissatisfied with them all: either they have great penmanship and are lousy lovers, or vice versa.
One day, at the Cafe Typo, Nagiko's favourite haunt, she meets Jerome (Ewan McGregor), a British translator. Intrigued by his knowledge, they go to a private space where she has Jerome write on her body in various languages. In spite of her interest, Nagiko dislikes Jerome's handwriting and orders him out. Jerome totally shocks Nagiko, however, when he asks her to teach him, offering her to write on his body. Opening his shirt, he offers Nagiko to "Use my body like the pages of a book. Of your book!". Nagiko has never considered this aspect in her desires before: her lovers always write on her body. When she backs out and runs, Jerome laughs at her.
Frightened but very intrigued by Jerome's suggestion, Nagiko has several one-night stands in which she experiments writing on their bodies. One of the activists, admirer Hoki (Yutaka Honda), a Japanese photographer who adores her, begs Nagiko to take him as a lover. She explains she can't, as his skin's no good for writing: whenever she writes on him, the ink smears and runs. Hoki, not wanting Nagiko to keep carrying on like she is, suggests she try writing a book, offering to take it to a renowned publisher he freelances for. Nagiko likes this idea and writes her first book.
Nagiko's book is returned, being told the book is "not worth the paper it's written on!". Insulted, Nagiko follows the address on the envelope to confront the publisher. Nagiko is shocked to discover that the publisher who rejected her work is in fact Yaji-san, her father's old publisher. What's more, the publisher has a young lover: Jerome.
Devising a plan, Nagiko decides that she will get to the publisher through Jerome. Meeting up with Jerome again, Nagiko discovers he has learned a few more languages, and his penmanship has greatly improved. Nagiko and Jerome spend several weeks exploring this, writing on each other and making love. Nagiko soon realises that, in Jerome, she has found the perfect lover she has been searching for: the partner with whom she can share her physical and her poetic passion, using each other's bodies as tablets for their art.
Writing of books 1 – 6
Nagiko tells Jerome the truth and the whole story with the publisher. Jerome comes up with an idea: Nagiko will write her book on Jerome's body and Jerome will take it to the publisher. Nagiko loves the idea, and writes Book 1: The Book of The Agenda, in intricate characters of black, red, and gold, on Jerome, keeping her identity anonymous. The plan is a success: Jerome sees the publisher and exhibits the book on his nude body, and the impressed publisher has his scriveners copy down the text.
After telling Nagiko of the plan's success, Jerome tells Nagiko that he'll return to her as soon as the publisher, who was extremely aroused by the experience, lets him go. However, during his time with the publisher, Jerome appears to lose track of time and doesn't return to Nagiko. Nagiko, jealous, impatient, and angry, searches for Jerome, eventually finding him making love with the publisher. Nagiko takes this as rejection and betrayal of the worst kind, and immediately plots revenge.
On two Swedish tourists (Wichert Dromkert and Martin Tukker), Nagiko writes Book 2: The Book of The Innocent and Book 3: The Book of the Idiot. Shortly afterwards, an old man (Wu Wei) is running naked through the streets from the publisher's shop, bearing Book 4: The Book of Impotence/Old Age. Book 5: The Book of the Exhibitionist is delivered by a boorish, fat, hyperactive American (Tom Kane; who was actually more interested in Hoki than Nagiko).
Nagiko's revenge is a success. Jerome is furiously jealous, and comes to Nagiko's home to confront her. Nagiko refuses to meet him, however, and won't let Jerome in. Jerome's outrage soon turns to desperation as he begs her to talk to him, but she won't.
Jerome sinks into deep depression and meets with Hoki at the Cafe Typo, desperate to find a way to get Nagiko to forgive him. Hoki suggests that he "scare" Nagiko by faking suicide, similar to the fake death scene in Romeo and Juliet and gives Jerome some pills.
Arriving at Nagiko's home while she is away, Jerome takes some of the pills, then writes a page, as if writing a book. Each time he takes some pills, he writes another page, keeping track of how many pills he takes on each page. As the pills take effect, Jerome can write no more and lies on the bed, naked, holding a copy of Sei Shōnagon's the book of observations.
The plan is a success: when Nagiko returns home and finds Jerome, she rushes to him, eager to renew their relationship and continue their plans. However, the plan has worked too well: Jerome has overdosed on the pills and is dead. Nagiko is devastated, and realises how much she loved him. On his dead body, Nagiko writes Book 6: The Book of the Lovers.
At Jerome's funeral, his mother (Barbara Lott), a snobbish, upper-class woman, tells Nagiko that Jerome always loved things that were "fashionable". When she suggests that was probably why Jerome loved Nagiko, Nagiko strikes her.
After the funeral, the publisher secretly exhumes Jerome's body from the tomb and has Jerome's skin, still bearing the writing, flayed and made into a grotesque pillow book of his own. Nagiko, now back in Japan, learns of the publisher's actions and becomes distraught and outraged. She sends a letter to the publisher, still keeping her identity a secret, demanding that particular book from the publisher's hands in exchange for the remaining books. The publisher, now obsessed with his mysterious writer and her work, agrees.
Writing of books 7 – 13
Nagiko, now pregnant with Jerome's child, writes Book 7: The Book of The Seducer on a male messenger. The writing on him is almost destroyed and undecipherable when the publisher accidentally leaves the messenger out in the rain. Book 8: The Book of Youth is delivered as a series of photographs. A young Buddhist monk (Kinya Tsuruyama) then arrives bearing Book 9: The Book of Secrets written on all his "secret" spots: in between his fingers and toes, the insides of his thighs, etc.; the book is presented in the form of riddles. When the next messenger (Rick Waney) arrives, he is completely bare: no writing at all. The publisher and staff search for any hint of writing on the messenger's naked body. As the publisher dismisses him as a hoax, the man sticks out his tongue, bearing Book 10: The Book of Silence.
The activists' protests come to an end when their truck hits a young wrestler (Eiichi Tanaka) bearing Book 11: The Book of The Betrayed, right outside the publisher's office. The next messenger (Masaru Matsuda) simply drives by the office, giving little time to copy down Book 12: The Book of False Starts.
Finally, Book 13: The Book of the Dead arrives on the body of a Sumo wrestler (Wataru Murofushi). In the book writing on the body of the messenger, which the publisher carefully reads, Nagiko finally reveals her identity, confronting the publisher with his crimes: blackmailing and disgracing her father, "corrupting" her husband, as well as Jerome, and what he's done to Jerome's corpse. The publisher, greatly shamed and humbled by being confronted with his guilt, hands the pillow book made of Jerome's skin to the messenger, then has the messenger slit his throat.
Upon recovering the book made out of Jerome's skin, Nagiko buries it under a Bonsai tree and life goes on. She has given birth to Jerome's child (Hikari Abe), and is shown in the epilogue writing on her child's face, like her father used to do when she was young, and quoting from her own pillow book. It is now Nagiko's 28th birthday.
Nagiko's bi-cultural heritage plays a key role in this film. As a half-Chinese and half-Japanese woman, Nagiko navigates her dual cultures through physical and psychological exploration. Greenaway portrays this exploration subtly by mixing and switching Asian iconography.