Fate
Fate—the development of events according to destiny and occurring beyond one's control—is the predominant theme in Kafka on the Shore. The incident that sets the plot of the novel in motion is Kafka's father's declaration that Kafka is fated to kill his father and sleep with his mother and sister. Wishing to escape this unpleasant fate, Kafka leaves home. However, he finds that forces beyond his control compel him to fulfill his father's dark prophecy. When Kafka meets Sakura, his attraction to her is bound up in the belief that she could be his sister. Similarly, he wonders if Miss Saeki—another woman he is hopelessly drawn toward—might be his mother. Kafka sleeps with both women, never sure whether they are his long-lost relatives or merely surrogates he was destined to meet. Kafka also discovers that he has blacked out and is covered in blood on the same night that his father was murdered. Although he couldn't have physically been present at the murder scene, Kafka believes that fate has made it so that he somehow killed his father by entering a dream portal. Fate also plays a pronounced role in Nakata's life. Bereft of the desires that usually motivate humans, Nakata operates according to ideas he spontaneously receives as commands from another world. He is compelled to perform the actions of opening the entrance stone and finding Miss Saeki for reasons he cannot explain beyond knowing that it is his destiny to set things right.
Existence of a Parallel World
Working in tandem with the theme of fate is the major theme of the existence of an alternate reality—a parallel world that exists alongside the world as most people know it. The parallel world seems to be the realm of the dead souls and of subconscious desires and evils. Murakami explores the theme of the existence of a parallel world by filling the pages of Kafka on the Shore with inexplicable supernatural phenomena and characters who function in both worlds. The character most emblematic of the existence of a parallel world is Nakata, whose childhood coma results in a portion of his soul leaving his body and traveling to the other world. Living in the real world with impaired cognition, a shadow that is only half as dark as regular people's, and the ability to speak with cats, Nakata eventually finds himself compelled by commands from the other world to set right the mysterious imbalance that has made the two worlds porous with each other. Nakata first has to open the portal to the other world by finding and flipping over the entrance stone. When he does, Kafka can go deep into limbo—the neutral space through which souls transit between life and death—to confront his subconscious fears. By the end of the story, Miss Saeki—who, like Nakata, lives divided between the worlds—dies, her soul moving entirely in the realm of the dead. Nakata dies as well, leaving behind the shell-like body he occupied in the world of the living.
Subconscious Desire
The major theme of subconscious desire complements fate and the existence of a parallel world. In addition to being a realm of dead souls, the parallel alternate world is entwined with the subconscious—the part of the human mind that influences a person's feelings and actions without the person's full awareness. When his father announces the Oedipal prophecy, Kafka worries that he will be unable to escape his fate because subconscious desires are bound up in the curse. Just as Oedipus unwittingly murdered his father and married his mother, Kafka worries that something deep inside him is guiding him toward a similar fate. Believing in the power of the subconscious, Kafka runs away from home so that he is unable to kill his father. However, Kafka finds that he may have killed his father in a dream, which can be interpreted as a window into the subconscious. Similarly, Kafka dreams that he rapes Sakura, and wakes up with the guilt of believing he has actually violated her simply by having imagined it. When Kafka visits the forest village in limbo, he can confront his subconscious and make peace with his fears.
Metaphysics
Metaphysics is another major theme in Kafka on the Shore. Broadly defined as the branch of philosophy that develops theories about abstract concepts existing beyond the physical or natural world, metaphysics and the metaphysical are directly referenced by characters several times in the text. Both Colonel Sanders and Johnnie Walker speak of themselves as metaphysical entities that exist beyond reason, beyond matter, and beyond morality; they merely take the physical forms they do in order to interact with humans. The parallel world of souls and the subconscious also exists as something that is beyond the known physical world. Ultimately, Murakami uses metaphysical incarnations to dramatize the interplay between the physical world that is explained by science and the inexplicable or supernatural phenomena that physical beings experience.
The Transformative Power of Music
The transformative power of music is another dominant theme in the novel. A theme seen in much of Murakami's work, music—usually classical and jazz—has the power to transport characters in their minds, helping them transcend their grounded physical experience. Music acts as an abstract language that stirs emotions and communicates the ineffable. In Kafka on the Shore, Hoshino's life changes after he happens to hear Beethoven's Archduke Trio for piano, violin, and cello in a café. Transfixed by the composition, Hoshino buys the record and listens to it obsessively in the apartment Colonel Sanders secures for him and Nakata. In contrast to the way the music reorients Hoshino's entire outlook on life, Nakata—whose soul departed him as a child—mentions that music has no effect on him: he experiences it as most people would experience the wind. With this detail, Murakami suggests that music communicates directly with the soul.
Taboo Sexuality
Alongside music, taboo sexuality is another of Murakami's trademark thematic concerns. As a fifteen-year-old pubescent boy, Kafka's thoughts are often drawn to sex. However, his Oedipal curse means he cannot experience attraction without filtering the attraction through his fear that whoever he is attracted to must be a long-lost relative. This first occurs when he meets Sakura on the bus and watches her sleeping body while thinking she might be his sister. She later gives him a hand job while asking him questions about his sister. The theme also arises when Kafka is attracted to Miss Saeki, who he suspects could be his mother. Rather than avoid her for this reason, Kafka finds himself powerless not to begin a sexual relationship with her. The theme comes up again when Kafka dreams that he is raping Sakura. Although he knows within the dream that what he is doing is wrong, he proceeds to have sex with her without her consent. Although he initially feared the curse that said he was destined to have sex with his relatives, by the end of the novel Kafka embraces his attraction to Miss Saeki and Sakura, and makes peace with the possibility that they could be his mother and sister.
Body-Soul Separation
The separation of the soul from the body is another major theme. After the traumatic incident on Rice Bowl Hill, Nakata wakes up from his coma without the personality, desires, or intelligence he formerly possessed. One of the examining medical professionals comments that Nakata's case reminds him of the literary trope from Tale of Genji that involved people's souls leaving their bodies. While the souls go off on a journey in the parallel world, the body of the person stays in the world of the living as a shell of the former self. Miss Saeki's soul also departs her body when her boyfriend dies when she is twenty. As a result, she comes off as aloof and distant to people who meet her in the real world. As evidence of their soul separation, both Nakata and Miss Saeki cast shadows only half as strong as regular people do.
