Comprising two distinct but interrelated plots, the narrative runs back and forth between both plots, taking up each plotline in alternating chapters.
The odd chapters tell the 15-year-old Kafka's story as he runs away from his father's house to escape an Oedipal curse and to embark upon a quest to find his mother and sister. After a series of adventures, he finds shelter in a quiet, private library in Takamatsu, run by the distant and aloof Miss Saeki and the intelligent and more welcoming Oshima. There he spends his days reading the unabridged Richard Francis Burton translation of One Thousand and One Nights and the collected works of Natsume Sōseki until the police begin inquiring after him in connection with a brutal murder.
The even chapters tell Nakata's story. Due to his uncanny abilities, he has found part-time work in his old age as a finder of lost cats (notably, Murakami's earlier work The Wind-Up Bird Chronicle also involves searching for a lost cat). The case of one particular lost cat puts him on a path that ultimately takes him far away from his home, ending up on the road for the first time in his life. He befriends a truck driver named Hoshino, who takes him on as a passenger in his truck and soon becomes very attached to the old man.
Kafka on the Shore demonstrates Murakami's typical blend of popular culture, mundane detail, magical realism, suspense, humor, an involved plot, and potent sexuality. It also features an increased emphasis on Japanese religious traditions, particularly Shinto. The main characters are significant departures from the typical protagonist of a Murakami novel, such as Toru Watanabe of Norwegian Wood and Toru Okada of The Wind-Up Bird Chronicle, who are typically in their 20s or 30s and have rather humdrum personalities. However, many of the same themes re-occur in Kafka on the Shore as were first developed in these and other previous novels.
The power and beauty of music as a communicative medium is a central theme of the novel—the very title comes from a pop song Kafka is given on a record in the library. The music of Beethoven, specifically the Archduke Trio is also used as a redemptive metaphor. Among other prominent themes are: the virtues of self-sufficiency and efficiency, the relation of dreams and reality, the specter of the heritage of World War II, the threat of fate, the uncertain grip of prophecy, and the power of nature.
Kafka Tamura: The character's true given name is never revealed to the reader. After having run away from home, he chooses the new name "Kafka", in honor of writer Franz Kafka. Kafka is a "cool, tall, fifteen-year-old boy lugging a backpack and a bunch of obsessions" and the son of the famous sculptor Koichi Tamura. His mother and sister left the family almost before he became conscious of them. He occasionally interacts with a hectoring, exhortative alter ego "The boy named Crow" ("Kafka" sounds like "kavka", which means "jackdaw", a crow-like bird, in Czech). Crow tells Kafka throughout the novel that he must be "the toughest fifteen-year-old in the world."
Satoru Nakata: Nakata lost many of his mental faculties when, as one of sixteen schoolchildren out on a mushroom-gathering field-trip toward the end of World War II, he was rendered unconscious following a mysterious flash of light in the sky . Unlike the other children, who lost consciousness briefly, Nakata remained unconscious for many weeks, and, upon finally awakening, found that his memory and his ability to read had disappeared, as well as his higher intellectual functions. In their place, Nakata found he was able to communicate with cats. Nakata and Kafka may also be different parts of the same person.
Oshima: A 21-year-old, gaytransgender man. He is a librarian and an owner of a mountain retreat who becomes close to Kafka throughout the course of the novel; also a haemophiliac.
Hoshino: A truck driver in his mid-twenties. He befriends Nakata, due to his resemblance to his own grandfather, and transports and assists Nakata towards his uncertain goal.
Miss Saeki: The manager of a private library, where Oshima works and where Kafka lives through much of the novel. She was previously a singer, and performed the song "Kafka on the Shore", which unites many of the novel's themes and gives it its title. She may also be Kafka's mother.
Sakura: A young woman Kafka meets on the bus who helps him later on. She may be his sister.
Johnnie Walker: A cat killer who plans to make a flute out of cats' souls. He may also be Kafka's father, the renowned sculptor Koichi Tamura. His name is taken from Johnnie Walker, a brand of Scotch whisky, and he dresses to appear like the man featured in the brand's logo. However, due to his similarity to a company symbol (much like Colonel Sanders) he may in fact be a "concept".
After the novel's release, Murakami's Japanese publisher invited readers to submit questions to its website on the meaning of the book. Murakami responded personally to around 1,200 of the 8,000 questions received.
In an interview posted on his English language website, Murakami says that the secret to understanding the novel lies in reading it several times: "Kafka on the Shore contains several riddles, but there aren't any solutions provided. Instead, several of these riddles combine, and through their interaction the possibility of a solution takes shape. And the form this solution takes will be different for each reader. To put it another way, the riddles function as part of the solution. It's hard to explain, but that's the kind of novel I set out to write".
Many fans of Haruki Murakami have come to agree Kafka on the Shore is better understood after reading Murakami's earlier works, especially Hard-Boiled Wonderland and The End of the World. Some long-time fans consider Kafka on the Shore to be a spiritual sequel to both Hard-Boiled Wonderland and The End of the World as well as The Wind-Up Bird Chronicle.